I'm in the same predicament except that it's not my bike, it's an abandoned one that's been sitting outside for at least 3 years. Locked to a pole with a kryptonite keeper. The chain, cassette, rims and hubs are completely corroded but the frame is pristine. I've already gotten the go-ahead from the cops telling me if I can get the lock off the bike is mine, now I just need to find a way to do it on a student's budget. I've seen plenty of posts about angle-grinders (too expensive for me) and hacksaws (already broke a friend's. I was wondering if I could superheat the tumblers and then cool them rapidly, aided by a hammer/chisel of course to disengage the lock. I have magnesium ribbon and air duster cans are pretty cheap.
Thoughts?
P.S. I'm NOT a bike thief, just a guy looking to give an abandoned and mistreated bike a new home.