One open air mining rig based off of an old core 2 quad.
     7850 - 320MHs
     7850 - 320MHs
     6850 - 300MHs
     5850 - 370MHs

And i couldn't help it, so i gave my server a radeon too.
     7950 - 605MHs

For a grand total of 1915MHs

To be honest though, through a lot of careful craigslist buying and selling, I think I have spent no more than $500