DC's used cd stores have declined in the past couple of years. Second Story Books, as mentioned is in Dupont Circle, has a wall of used cds, but it is all old stock, nothing fresh coming in. There were numerous CD Game Exchange stores, but many have closed, leaving two -- one in Silver Spring, near the SS metro, and the other in College Park. Neither store is well kept, and recently I saw a sign on the College Park door stating that for unforseen reasons they cannot accept trade ins. Not good. Cdepot, also in College Park, is massive, but it is a mess. You can barely walk throughout the store without stumbling over a box of crappy 12" dance or hip hop records. Their stock of used cds have gone down as well, and their prices seem to have gone up. Joe's Record Paradise, up in Rockville, is okay, but like any used store, is only as good as their stock, and they seem to be on a lull for decent jazz right now. Plus, they are moving to Silver Spring, but where or when is to be determined. Orpheus does not exist -- however, CdCellar, which has stores in Clarendon (near the metro) and in Falls Church, are the only used stores that seem to be doing okay, in that they get promos and fresh new stock of used goods weekly. There is also Record and Tape Exchange in Fairfax, but their prices are way too high - too much studying the OOP prices on Amazon.
There used to be other stores (like a Second Story in Bethesda, music stores in Adam's Morgan. etc.) but all have closed their doors. It's all online now.