well 775 is what i currently have. i would guess that there wont be any refurbish "i" series boards so i have to go with 775. i have a dual core with ddr 2 and some stupid biostar board. couple years ago i got a Asus maximus formula for like R500 lol
There seems to be quite a few new ones out there for well under R1000 - any particular specs you need? Have a look at Nivo for a few examples - there's a few of the Asus, Intel and MSI seem to support DDR2.
I'm sure a few of the resellers here may also be able to assist you with something.