The pots are about four inches tall, and quite solidly made. Empty ones could serve as nice little vases or general knick-knacks and could easily go for a dollar or two apiece, or more, in a U.S. housewares store. Here each yogurt plus its pot costs two and a half RMB (35 US cents). It's either two RMB (28 cents) for the yogurt and one-half RMB (7 cents) for the pot, or vice versa. My wife didn't remember which the sign said. We're building up quite a supply. Maybe the foundation of a specialty-import business if we can get them back to America? The spirit of Chinese entrepreneurialism is infectious.
Update: Several correspondents have usefully pointed out that the pots can be returned for a deposit, just like beer bottles. Makes sense! It turns out that my wife knew this (I have never bought them myself) but just didn't mention it to me! Now I know -- the real communications problems are within one language, not across language boundaries -- and we can haul a bunch of them back to the store for pockets full of cash.