It really depends on who holds the judgment. I have heard that some companies will settle for less. It definitely doesn't hurt to try.
I tried to do that with Midland and they wouldn't budge.
As far as how much to offer.....that's going to be up to you. You may want to start a little less than what you want to pay and let them give you a counter offer.......and possibly meet them half way.
Sorry......don't feel like I was much help. Hopefully they will work with you though. Good luck.