Mark, I don't really know what forces are driving the prices for spare parts, but I can make a blind guess. Honda parts, in my experience anyway, are expensive from Honda dealers. Non-genuine Honda parts are around half of Honda's prices or less, on ebay. This happens because they are made by the people who supply the parts for chondas. The result, in my experience anyway, is good parts at low cost. (I'm not saying there aren't any bad parts being sold, of course: you have to know what you are buying.)
There are non-genuine Briggs rings being sold on ebay, but by American sellers, so the postage cost makes them over-priced here. My guess is there aren't many local sellers of non-genuine Briggs rings because Briggs engines are mostly side-valve with aluminium bores, and don't have their rings replaced all that often because the bores are too worn to make that worthwhile. Now that the side valve Briggs engines are all made in China, I'm guessing that non-genuine spare parts for them will become as cheap as Honda ones, but the aluminium bore engines still won't be worth re-ringing, because of the bore wear. It may not be worthwhile selling the rings just for the relatively few which (like yours) have cast iron bore liners. It may be a while before this situation resolves itself anyway because the large side valve engines were only moved to China about 2 years ago, much later than the small side valve engines. The local ring producers there may still be getting up to speed at this stage.
