Richard
You may well find it worthwhile listing the build manuals, and other items, on ebay. I think many people use it as their first port of call and don't research the availability elsewhere.
If you register as a business seller you only pay the listing fee once, and can quote a stock level of say 100, so it is ongoing. Sell as Buy it Now only and quote "immediate payment required". Very little ongoing work is required as long as you check your purchases daily so as not to delay dispatch.
Walter