Thanks! Isn't there also a second hand clothes store in Bethesda called Mustard Seed or something like that?? There is also a second hand consignment shop in Dupont called Secondi which is not all that cheap but I have found a few things there anyway. But really it is somewhat expensive, and I have found things at the Ann Taylor loft store further down the street on sale at a better price than at Secondi.
Yeah, Mustard Seed is in Bethesda; it's really close to the metro station. It's not really a thrift store though--they are really picky about what kinds of clothes they sell--they have to be fashionable, etc. It's not that cheap either. A tee-shirt might cost $5-8. They also sell thrift shop clothes with jacked up prices.
Half of the store is devoted to new clothes also. I like Deja New, I've found some nice stuff there.