As far as Seiko is concerned, probably the best choice will be on Ebay (assuming you are not prepared to dabble with Yahoo Japan) but there would be a very good chance you'd then need to spend money (or end up with a clunker). Most of the UK Ebay sellers specialising in so-called restored vintage Seiko's are just hawking recycled Philippines junk. The SCWF sales corner is a possibility but choice will be slim if you are looking for a particular year and in my experience it is no safer a place to buy than Ebay. Your best bet is to do what you've done already, and post a WTB here, hopefully then netting something which has already been serviced and good to go.
Martin