plenty of people just around the PNW, first off.
Pretty much everyone on Massline records (blue scholars, gabriel teodros, common market, etc. etc.), myself (haha claim).
Everywhere else: DL Incognito, Terminal Illness, Brother Ali, Jedi Mind Tricks...plenty of 'underground' artists self-produce. Many do get help from professionals, but the ones that self produce are often the ones with the most thought-provoking, most technical music in terms of rhythm and bass lines and all. their musicality is at a high level as opposed to someone such as Lil Wayne or Young Buck. Not hating on them, some of their music is really fun to listen to, but musically speaking it's pretty horrific.