Nip into WH Smith and have a covert look through some of the waterways magazines. Bukh are sometimes used on canal boats and inland suppliers seem a bit less rapacious than marine ones. You might find someone advertisng. I know I was miffed at seeing a Morse control advertised for about 2/3rds what I paid in Lymington!
Be careful- for instance, water pump seals can be obtained cheaper but they may have carbon or stainless steel springs and only last a few hours running, result -water in the oil sump.The seals suppllied by Bukh have hydro dynamic lips and are fitted with phosphor bronze springs.