Best Bang for the Buck GPU for 2009 MacPro

I'm helping a client with a late 2009 MacPro running FCPX and Motion. Currently they have a GeForce GT 120 with 512MB. What would be the best bang for the buck for a new GPU?

Do they want a legit Mac card? The 7950 at $460 is a great card at a not so great price. Plus they are hard to find.

Macvidcards on ebay has mac rom flashed PC cards for much less. Their 7950 is $350.

Their cards support the boot screen and are recognized as a native Mac card. I haven't done this myself.

They also have a variety of Nvidia options, although they are much more expensive.

Dual Radeon 5770s. I'm actually using two PC versions of the cards. The tails are too long to fit in the Mac Pro, so you will have to use a hacksaw to shorten them. I know you just LOLed when you read that, but it works and it saves you a few hundred dollars instead of buying the Mac versions. Both cards work great and I got them for around $175 together on eBay.

If you don't want to bring out the hacksaw, then I still would suggest getting two of the Mac versions. You will just pay a few hundred more for the set.

I just stuck PC GTX680's in our old MacPro's - all it needed was an extra PCIe power cable via eBay.
The only downside is that you don't get any boot screen - just the OS-X login windows onwards. This could be a problem but after doing it a year ago I've never once had the machine completely fall over and wish I could see the boot 'grey' screen.

If the client is only using FCPX and Motion 5, then two 5770's would be the best bang for the buck. Try to find them a second single slot card for best results.