The Framingham, MA Target has Gears of War (the original) for the 360 on clearance, for $19.98. It's the one with the bonus disc with Gears 2 previews, etc. When I picked one up there were about 5 left. Marlboro reportedly doesn't have any, and Westboro has them for more like $30.
Just a heads up that I picked up a copy of Fallout 3 PC (new) from ebay for about $40. This was the seller: http://shop.ebay.com/merchant/obsidian_inc_W0QQ_nkwZQQ_armrsZ1QQ_fromZQQ_mdoZ
It's really not too complicated - you would probably be able to figure it out on your own, since it's mostly an issue of putting things in sockets and connecting power cables and stuff. This guide looks pretty good at a glance and you can find plenty more with a quick Google search.
In my...