i made a thread similar a while ago and i ended up ringing around about ten different turbo companys. Midlands Turbos wasnt the cheapest i found however, the feedback from people on the forums that have used them is enough to make you want to pay that little bit extra. I think the difference from them to the cheapest was only around £50-£70.
They seem like a reliable company and comes with 1-2 years guarantee, i will be purchasing my reconned turbo from there soon. i believe it was around £370 which included vat and delivery but they also do a thing for around £150 where they pick up your turbo and fix it if possible?
Wouldn't touch them cheap ebay parts! a friend of mine did it and the quality was awful, it went on him again within a few months of fixing.