Have used Hahne for LOTS of stuff for racing - they're one of the cheapest sources around for carb parts etc. Also accept payment by paypal. Comes with the highest recommendation from me... I've posted about em quite a lot in the CBR125 section... never thought to shove a link for em in here.
Just fire em an email with list of parts that you want, and he'll give u the total and paypal address to fire payment off to. Example: Mikuni TM28-1 from Topham (main European Distributor for Mikuni) cost ?162. From Hahne - cost ?132 - and it came thru with a Topham sticker on it.
Shipping is dirt cheap, and stuff tends to arrive within 7 days of payment being made.