This may not be standard advice, but if the heatsink is fine, you can usually just strap on any old fan and it will be fine.
It may not connect to the power connectors on the card as they're usually 2 pin and sometimes an odd size, but a spare motherboard or PSU connector will do the job (depending on the type of connector on the fan).
The size for an FX5200 heatsink is likely to be 30-60mm (that's a pure guess based on ... instinct, I guess you'd call it ... I don't know what kind of cooling system your card has).
I'm a big fan of improvisation, and whilst it's not the best solution for everyone, it works for me.
Example: My Radeon 8500LE, with a Northbridge heatsink held down with thermal paste and a few drops of superglue at the edges, with a 40mm fan hanging on the edge with a screw. Works perfectly. Your mileage may vary.