For blues, blues reissues and some other interesting stuff, Redlick Records are good. Their website, www.redlick.co.uk, is naff - no track listings, and half the orders placed on the website get lost   (ie. they don't send them because they don't know you've placed them). But find what you are looking for there and it costs less than elsewhere, make a telephone order and it's there in a couple of days. Very good for international orders, too.