Re: Get a key for the lock
I think everyone has covered your options. I'll just add another vote for trying to pick them. It really isn't that hard, and once you get the hang of it, you'll find yourself trying different locks for fun. Depending on the style lock, I've had good success with nothing more than a bent paperclip and a small screwdriver.
Once picked, you should be able to replace the core or the entire lock, but as said before, you have to get it unlocked first. One caution, after you spend 30 - 45 minutes picking it, put a block of wood in the way so it won't close on you and force you to pick it again - been there, done that!