I'll generally tell them it's really not my specialty, give them a 'ballpark' answer with three or four 'but on the other hands,' recommend that they not rely too heavily on my opinion, and then suggest they consult a specialist for more information. (Can you tell that I used to practice law? Guess I'll have to become an auctioneer for my next career.

Then I can say the same thing only faster.)
Most of what I sell is in this category. I use the famous Goldberg Formula for determining initial price level:
First calculate price A, which is the median price point for the category (in your case, perfume bottles). Then take price B, which is the price that you paid for the item, and multiply by factor C, which ranges from 2 to 10, depending on the amount of price B. (If I got it in a $1 box lot, I use 10 as the multiplier. If I paid over $500 for it, I use 2). Add the product of price B and factor C to price A, then add this sum to price D, which is the price you would pay for the item if you had unlimited funds and were buying it to keep in your house. (For stuff I don't like, price D is zero; for stuff that I'd really rather keep than sell, price D can be in the thousands.) This will give you sum E, which you will then divide by 3 to get price F. To price F, add or substract adjustment G, which is the arbitrary amount that is needed to increase or decrease the price to whatever you feel in your gut that the piece is worth. The result is price H, which you should then write on price tag I.
If the item has not sold after six months, double price H to get price J, and write out a new price tag K. If the item still hasn't sold after another three months, and price J is greater than price D, then use red magic marker L to mark it back down to price H, still using price tag K. If it hasn't sold after another three months, and price H was greater than price D, once again use magic marker L to mark it down to price M, which is half of price H. If price H was less than price D, take the item home and put it on shelf Nin your living room O.
Many thanks to Mr. Goldberg, owner of Rube's Antiques, who developed this universal pricing formula.
