If by purchase you mean figure out your local library has an amazing collection of blues, my favorite cd's are burned copies of the best of Muddy Waters, Buddy Guy's "Damn Right I Got the Blues", and other titles by John Lee Hooker, Albert Collins, B.B. King, Robert Cray, Eric Clapton, SBW II, R.L. Burnside, and a couple very nice compilation albums just to name a few.