Considering 25K miles almost covers a round-trip upgrade in the US (including Hawaii), I'd say $100 or $150 would be worth it. Of course, YMMV.

FWIW, I recently just got back 90K miles for an award trip I booked in C to SYD back in 2004. I had cancelled the ticket, paid the redeposit fee since I was a GM then (in those days a 'mere' $75), but I never got the mileage back. It was a bit of a challenge (ever had to dig up a Credit Card statement from March 2004?), but in the end I received a call from a MP SD who was exceptionally professional, cordial, and apologetic.