I just serviced my engine with spares sourced from an eBay shop called Marine and Leisure Supplies:

http://stores.ebay.co.uk...ine-and-Leisure-Supplies 

It was all good quality stuff, very quickly dispatched and very reasonably priced (for example his service kit for my 14hp Beta is under fifty quid including the postage, as against Beta's "short voyage spares kit" which contains most of the same things at close to £100 if I remember correctly). The original total included three lots of P&P but he sent the lot in one package, combined the postage and issued a refund on the unused postage the same day as the order, all without being asked. Most impressed and will use again.

Incidentally he does spares/servicing kits for various engines of various sizes - Volvo Penta, Bukh, Beta, Yanmar and Nanni, among others.

All the best
Graham