Joe what comp are you talking about? I can actually not think of the last well put together comp with good bands and exclusive songs, which i think is a large reason people dont "buy comps anymore"... because they don't exist, or are just some bogus CDr with already released songs by everyones friends bands. I think a lot of bands on this comp should realistically have no problem selling 100 copies to their particular audience because they have an exclusive song on here. I think 1,000 will go quickly.
I've thought for a while a labels like Dirtnap, or Don Giovanni, or It's Alive should do a well put together comp with their bands full of exclusive songs. I personally am a fan of comps and wish more good ones were being done. As long as it's not throw away songs, but good material, it'll sell.