Both Mini Spares and Somerford have been good for me so far.
Not long had my mini but I have spent a lot of money with Minispares on body panels, their service is top notch and their packaging to protect the panels is second to none.
I also went to somerford in Calne while on holiday at my mothers and Pete behind the counter sold me some cheap front wheel bearings, telling me "we use them on our restoration cars". I went out and spoke to the guys that rework the minis and they said they only use timken bearings !!!
I have now decided to try and reuse as much of the original parts from my mini that I can.