If you're up to it, here's a fix posted by someone else:

http://au.geocities.com/ozbrick850/door-stay_fix.html

I had the exact same problem and saw that my hinge was split inside the door and the welding came loose. Took it to the dealership because it was covered under warranty at the time. The fix they did was exactly what was above + welding.

It cost $50 because it was covered under the VIP warranty and I had other things done under warranty too. Amazing, the parts to fix were just $8. The labor would have been another $100.

Doesn't hurt to at least get an estimate (they should do plenty of them). Or have an hour or so ready on a Saturday.