The cap nut for the shocks appears to be available here, if you're preferring to buy new:
80 cents:
http://www.hondapartsnow.com/genuine...021-10020.html
79 cents:
http://www.powersportsplus.com/parts...-10020-0S.html
I did see a pair of NOS nuts available on eBay in Great Britain, but the postage makes them a tad pricey. Hopefully one of the North American sites actually has them in stock. Lots of web sites seem to have no idea what's really in stock until you attempt to buy the part.
Good luck.