I am looking to buy a graphics card and was looking at VisionTek Radeon HD 6950 Graphics card (only because this one should go pretty cheap) but it is currently bricked.

This is the exact wording of the person,
"This graphics card is bricked meaning a bios flash gone wrong. I do not have the time to do the research and get it fixed, My lost if your gain.
The card has been tested in a PC, It was seen by the system but no output when connected to display. Fan spins up fine.
The item is in excellent condition physically. The original box will be included."

I am wondering if it is possible to fix this. If so, how hard would it be? Is it worth it?

Leave this one at phone pole length... You can get decent (and new) video cards for between $50 and $100 USD from many on-line stores, although I'll grant that this one will cost you between $250 and $300 (about $300 USD at buy.com - http://www.buy.com/prod/visiontek-900352-radeon-6950-graphic-card-800-mhz-core-2-gb-gddr5/219360590.html). Before you buy this "brick", I would suggest that you do the research and figure out whether or not you and unbrick it, and whether or not you are willing to flush the $$ the card will cost you if you can't fix it.

Do bear in mind that this card requires two PCI slots.