If you knew what you were doing...

1. You would know what computer model you purchased.
2. You wouldn't have bought that computer in that condition.
3. You wouldn't have broken the video card during disassembly.
4. You wouldn't need our help if you knew what your doing.

My Mac Pro Quad 2.66GHz was $2360. I don't know how you came to the conclusion it's worth $10000.

If you are willing to pay whatever to fix it, take it to an Apple store or authorized repair shop and let them take of the repair. Or consult the almighty google for your parts needs. There is no shop (that I know of) that sells Mac Pro replacent parts.