Same, I play a lot of original folk music and most songwriters are giving away their CDs in about a 1/3 of the transactions I've seen. The other 1/3 of sales are more like tipping for service workers, and the other 1/3 is genuine "folks want the music and they want to pay for it.
The difference I believe is that activity seems more reactive than preemptive. Case in point, the mixtape as a precursor to the album, which exists primarily as a promotional vehicle. Even rappers that have already made it continue to do mixtapes for more experimental work or as a thank you to their fans.
I've got quite a few CD's like that. So I'd say - plenty.