Almost every entertainment attraction sells shot glasses as a souvenir in their gift shops.
Shot Glasses come in every color you can imagine. While most are the same size there are some that are taller and some that are shorter than a standard shot glass. I've seen them made of many materials, a few being glass, porcelain, wood, metal and plastic.
Alcohol manufactures use shot glasses for lucrative advertising, the lucrative part is that people pay for the opportunity to purchase business advertising on souvenir shot glasses.
Shops that carry state or city souvenir items usually have shot glasses. Flea markets are also a prime place to look for shot glasses. Collectors seem to either buy all they see or they collect a series of particular shot glasses. For instance, we had a collector that came into the store looking for shot glasses with football team logos. Another buyer was looking for any shot glass with a alcohol company logo. We also had several young men that bought every one they found.
I do come across them at yard sales occasionally where you can usually pick them up very cheap. Once I bought a huge lot of shot glasses at a yard sale for 10 cents a piece and sold them as a lot on eBay for $75. A huge profit for me.
I usually price my shot glasses between $3 - $5 in my flea market booth and I have no problem selling them.