275
I Put a Datacenter GPU in My Gaming PC for £200
(blog.tymscar.com)
This is a most excellent place for technology news and articles.
A lot of data center GPUs don't have display outputs or cooling. So you would need to figure out how to cool them.
Cooling wouldn't be too hard, I'm currently overengineering an Xbox 360 for that so I've done a good deal of learning. Getting of to display video is outside my skillset though.