option for CH to tip winning designer

There is an option on a couple of other sites for the Contest Holder to add a tip for the winning designer at finalization.  Would be nice for the CH to be able to throw you a little extra $$ for any post-contest work or if they feel you've earned it otherwise.

Might be a lot of work to implement this feature but it would be a nice bonus for designers that go above and beyond expectations.  This would likely create a situation where designers tend to go above and beyond, be more timely, and be more responsive (because they know there might be some extra $$ for them) - This would result in increased customer satisfaction, retention, and referral.

Thoughts?

On our site the client can increase the contest prize anytime before closing contests and also hire you in a 1on1 project. Our site allows client/designer to work together on minor work/changes in finalization area for  7 days. On our site...if the changes to winning design are major or go over the   7 days then  it is suggested to  open a  1 on 1 project with winning designer where client and designer negotiate the dollar amount for the added work