Nate, Most of my buybacks are from the original 2002 Topps T206 run. Not sure if it is just my luck or if the Series 2 Light Blue cards are more plentiful. But I seem to have the most from that series. Don't forget that there are also buybacks released as Topps Baseball History available in 2008 Topps Updates & Highlights at 1:1,384 Packs (I think hobby boxes are around $40). Not sure if it is worth it or not at those odds... Also the 2010 product has buybacks of buybacks, which I still don't know why Topps did I was hoping they would have used the white frames, like the GU and Autos, but I guess they took the easy out and just put in 2002 buybacks from all 3 series with no special markings (like buyback-buyback)....
2008 Topps Updates & Highlights Buyback