Well, speaking of Clifford Brown jam sessions, you can get his final recordings, from the night he died, for $3. The last 3 tracks of The Beginning and the End are that Philly jam session. You can skip the first 2 short R&B tracks that he makes a brief appearance on before his first jazz recordings.
http://www.amazon.com/The-Beginning-And-End/dp/B00138HAGA/ref=sr_shvl_album_1
Mingus in Europe, $2.67
http://www.amazon.com/gp/product/B002LD41JU/ref=sr_1_album_45_rd
An Evening With Joe Henderson, Al Foster, Charlie Haden, $3.56
http://www.amazon.com/gp/product/B001O0VDLA/ref=sr_1_album_7_rd