http://www.ebay.com/itm/Hitachi-LG-Sata-CD-RW-DVD-Rom-Drive-Model-GCC-H30N-/110978873085?pt=US_CD_DVD_Blu_Ray_Drives&hash=item19d6db36fd
http://www.newegg.com/Product/Product.aspx?Item=N82E16817171031
http://www.newegg.com/Product/Product.aspx?Item=N82E16817171031
You should be a little under budget.
I even think you could get the 7870.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150604