I think karma can get you some great stuff.
Ive used my karama on Orr temple armor set (looks terrible but you transmute it to something nice). In Borderlands there is a vendor selling weapon, armors and trinkets. Ive gotten LB and trinkets there. Think ive spendt around 350K karma by now. And im not done yet.
I also use karma in wvwvw for upgrades.