the original plan was to kill him, obviously because they dug the hole. When Frank gives up the dough, Gonzalez says something like "that buys you something", and they begin to leave (i believe they were legit leaving). Frank asks for a lift, that's when homie tells Gonzalez he wants the suit, and they try to punk him again.

Now at THAT point, I think Frank's dead weather he gives up the suit or not