I was reading past threads about S*UAL/DENIED-VDB and it helped me a lot. The one answer I could not get is about how much the ticket is worth. UA seems to give either $200 or $400 and up to $600 I think.

If for example you give up your seat, they give you a free ticket and then you go to CS and get it changed to a credit voucher (to avoid a gate hassel), how do they decide how much you get?