Seasonic manufacture their own PSU's and are certainly in the top two or three for sure.
Corsair use many different OEMs to build their PSU's the 1200i is Flextronics in this instance.
In the UK it is best to look on Deal of the Day at scan.co.uk or Aria specials. Actually any of the main online retailers will have deals for PSU. OCUK do a daily special that is worth checking out too.
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