Nomad Terror
Rear Admiral
I would of done the same if I had the cash but to be honest its just as easy as putting a new cpu into a pc, the shop I did ask about it I tell me they couldn't guarantee that they can fix them all the time but as I've ha this xbox since 2006 I did it myself and it works fine now. As for tools all you need are some torq drivers I thinks its t8 and t10.
I'm not familiar with hardware stores on that side of the pond, but over on this side, Harbor Freight has some rather nice Torx sets for pretty affordable prices.
http://www.harborfreight.com/pack-of-3-folding-star-bit-and-sae-metric-hex-keys-94905.html
http://www.harborfreight.com/7-pc-mni-star-tamper-proof-key-set-97469.html
I own these two, specifically. They can be disassembled to use the keys individually or just folded out of the set. I haven't needed a Torx key that wasn't on one of these sets.