Looks like it will go for around $200.
Here:
http://www.buy.com/prod/radeon-4850-512mb-gddr3-pcie/q/loc/101/208177814.html
And
http://www.neutronexpress.com/prod.cfm/823786/VISIONTEK/900241/RADEON_512MB_PCIE
Here:
http://www.buy.com/prod/radeon-4850-512mb-gddr3-pcie/q/loc/101/208177814.html
And
http://www.neutronexpress.com/prod.cfm/823786/VISIONTEK/900241/RADEON_512MB_PCIE