Tell them to sh!t or get off the pot.
Either they want gold leaf, which is expensive and not many can gild glass..... or they settle for imitation gold leaf vinyl for what it costs.
Seeing your other thread about this customer and now this one, it seems evident, you don't have as good a grasp on the many materials and substrates available in this industry as you need to deal with customers.
You're tending to allow the customer to walk over you and dictate how you should conduct your business. You need to give them their possibilities and they either take it or leave it and then you don't have to waste hours looking up crap for nothing.
If this was a multi-thousand dollar job, you could waste an hour or two..... or three, but you're having trouble getting $500. You're already used up all your profit and you still don't know what you're going to do. Besides, do you have the job ??
If you're still gonna use gold leaf vinyl, you realize you have to back it up with cast black ?? Ya can't use calendared... it will shrink wa-a-ay too fast.