Returning for the Demo...
Great! -- the dealer has called and wants to see your "live" demonstration.
He has watched your video and given it some thought. He is ready to talk to you about it.

Important - you should never let the dealer pick out a demo car. He would probably choose the nastiest car on his lot.
If he does... Just say "Not a problem -- I can show you how anyone can handle a car like this. It just takes a bit longer because there is an extra step involved."
"But instead of focusing on one bad car, I want to demonstrate how cheap and easy it is to make 99% of your cars look showroom new again. It takes less than 2 minutes per car. Because, after all, this is where you are making 99% of your money."
Pick out a car with normal oxidation and no yellowing. Hondas and Toyotas are the best examples.
You are now totally in control.
Explain that you normally refinish a headlight after each car has been freshly washed in the dealership's "clean-up" area. But for today, I will just use this damp cloth to wipe off any surface dust.
Time for the "60 second" demo...
"Watch as I wipe on Klearstar and wipe away all the oxidation."
"Now the car looks showroom new."
"It's that easy. That's all you have to do. Before I do the opposite headlight, let me take a pic and show you how much better this car will look in a photo ad."

Important - immediately take a full front photo of this car as you would for an Internet ad. Text the photo to the manager's phone.
Let him see the difference in an actual, side by side, photo comparison. Ask him if his Internet photos would look better and see what he says.
You did say my cost is $4.75/ea right?
"Yes. $4.75 per headlight is the wholesale price for a carton of Klearstar.
But get ready --
Car Dealers love to negotiate. They think they are experts at getting a better price from vendors. Smile. Let them believe it.
How many in a carton?
Tell him "a carton does 50 cars or 100 headlights"
If he makes a lower offer, then you need to make a counter offer. Pause, take time to think, then tell him you could give him the 50 car price for just 25 cars.
He still wants a better deal? Pause again. Think. Offer him the 50 car price on 20 cars.

You must always be prepared to walk away without an order if a dealer keeps insisting on a better price. (It is not a big deal. There are 40,000 used car dealers in the USA.)
But here's how to end it.
What works best is to say -- "we both are serious business people and in order to have a relationship that works, we need a mutual transaction that makes sense for both of us."
"I have already given you the lowest price I can. I am afraid I can't do any better. Don't you think $4.75 per headlight is a fair price, especially for only 20 cars?
(after all, it was his idea to call, knowing full well your price was a bargain at $4.75 per headlight.)
If he still won't agree... just thank him for his time and be prepared to leave. Then see what happens.
More likely he may try a different angle to regain control of the negotiation -- Look, I like you and I like your product, but I don't want to do the work myself. I want you to do it. I will even pay you $5 per headlight.
Again, pause and think before speaking. Tell him you might possibly do $6 per headlight if you could count on refinishing 10 vehicles each time you visit.
"$6 per headlight only gives me $1.25 for my labor. I would need that extra $1.25 just to cover my travel costs. $1.25 x 20 headlights is only $25. Charging $6 is the same as agreeing to do the work for free."
He can't argue with that logic.
When all else fails...
If a Car Dealer says he liked your product, but keeps getting stuck on wanting a lower price (but you need to leave without a sale...) There is still one, final tactic remaining.
You could tell the dealer that if he didn't care if his headlights only looked new for the next 60 days, he could get 2 cars refinished from one bottle!
This would certainly get his attention because his expense per car would instantly drop in half to $2.38 per headlight.
Show him the bottle you used for his demo. Show him how you purposely only used half of it for demo purposes.
However, be sure to let the Dealer know that if you did this at your Service Center, you would instantly KILL your business and drive customers away forever, because people who pay $40 for this service always expect refinished headlights to last longer than 60 days.
But, in his case, since he is not charging for the service, but merely using Klearstar as a temporary dressing, he could simply choose to use a lesser amount.

Here is a selling tip:
Tell the Car Dealer that giving each car new headlights is actually cheaper than washing the car.
Car Dealers know their numbers. Show him how smart you are.
Ask the dealer if he knows how much he pays to wash each car? See what he says...
The cost of supplies may only be a dollar or two, but the major cost is 10 or 15 minutes of labor. Even if the dealer only pays minimum wage, he still needs someone to drive the car into the cleanup area, wash the car and drive the car back out to its parking space.
Now tell him -- You just saw how it only takes a minute to give a car new headlights. Plus, you only need to do it once. A car must get washed at least twice, if not several times before it leaves the lot. Once, when the car first comes in, plus at least once again at delivery to the buyer.
Once you factor in the actual labor cost and do the math -- it costs more to wash a car than it does to give the car new headlights! New headlights only take a minute. The labor cost is close to zero.

How much money do you actually make?
This is what the math says:
a Box of 25 bottles of Klearstar at $4.75 (or $2.38) per headlight, costs the dealer $237.50. Your cost is $112.50. That means - you earn $125 on his initial order and keep earning $125 in less than a minute, every time he reorders.
a Box of 20 bottles of Klearstar at $4.75 (or $2.38) per headlight, costs the dealer $190. Your cost is $90.00. Again, you earn $100 on this order and you earn $100 in less than a minute, every time he reorders.
Meanwhile, if you agree to do the work yourself:
For 10 cars, at $6 per headlight, you get paid $120. Your cost is $45.
Since it only takes a couple of minutes to wipe both headlights with Klearstar --
You earn $75 for 30 or 40 minutes of your time.
$75 for 30 minutes = $150/hr.
$75 for 45 minutes = $100/hr.

Learn to negotiate like a pro and earn a ton of money! The key is to be knowledgeable, confident and always speak like the experienced professional that you are.

Addendum:
Sometimes you need to deal with yellowing headlights, especially if the dealer you are working with specializes in cheaper, much older vehicles.
You should show these dealers how they can bleach the yellow out by using Soft Comet with Bleach before wiping with Klearstar.
You will also need to explain how Klearstar fixes "environmental damage" only.
It will not repair man-made damage from WD-40, lighter fluid, bug spray or spray painted clear-coat, etc. Show them how to test for man-made damage.