+Minx-girl.com!
I get their newsletters and have bought some fantastic top-brand stuff in whenever they run one of their fabulous sales! There are always items in the Sale section of the website, year round, though if there isn't an official Sale going on, stock runs really low and you won't necessarily find the size/colour you want.

One thing that really makes Minx-girl.com stand out is the customer service. Debbie is the 'head Minx girl' and she is always available to chat with over the phone when you can't decide between a choice of several items or need advice on fabric, fit, etc. She spent half an hour on the phone with me one Sunday afternoon discussing 3/4 length 'baggies' - I went with her recommendation and love them.

One thing hebe - they don't have a shop you can visit (or a catalogue as stock changes so rapidly) - it's strictly Internet with mail order delivery.

And yes, I trawl eBay a lot too. Set up automatic searches on categories or brands you're interested in - makes it easier to run a fresh search whenever you want, or to sign up to automatic e-mail notifications when new things are listed.

oh and yes, +1 on merino base layers AND socks. Makes so much difference in these English winters.

Happy shopping!