I don't know if it's the cheapest place to get stuff but my local snowmobile shop has been hooking me up on almost every thing at reasonable prices ( I don't think they mark it up much for me), The Honda shop still has my right arm for the first set of rings I bought there a few years ago. The snow mobile shop uses a site that ryhms with Dracula,not exactly sure, but, the prices haven't hurt as much thru them ,they"re all OEM . That would be for rings ,bearings,extra seals that don't come with complete seal kits. Motion Pro for the cables. Vesurah gasket complete kits around $65 (comes with no gaskets for the crankcase) Honda wants $65 for the head gasket alone ( did that once ) Veserahs kit is the 550 kit and you'll have to order a clutch side separately for a 500. The last time I looked the crank gaskets were not avail. for 500 thru Honda...But...1980 cb 650 has the same crank gaskets and are still available. Crank/rod bearings are getting hard to find depending on which letter your rods are and what color code your crank is,...very personal information like that. I haven't found a crossover for that stuff yet ,But you can bet that somebody on this site has. Always get a shifting rod gasket unless you like automatic chain oil and slippery garage floors. Vaccume gauges for sinc'ing carbs are no more expensive than having a Honda tech do it once,and it's a tool you can keep and reuse. I 'm making the switch to Alan heads because screws suck and there has been a kit on E Bay for around $40. I have multiple engines so I have a shop kit that I refill regularly. The metric "auto parts stores " 'O' rings don't fit your model engine on neither the bottom or the top of the jug, and you 'll need those O rings( they come in the vesurah kit as does valve seals ). If another reader knows of a better place to get/ product to get , please chime in now.