realistically, you may not need any shims at all. If they're all in spec, which is common, you won't need any. If one or two are out of adjustment, you can sometimes swap them around from one valve to another. If that's not possible and you just need one or two, they're usually about $5 or so from any dealer (doesn't have to be Honda), but I haven't priced them for a while so I'm not sure what the current costs are. Regarding other parts, sometimes the valve cover gaskets will re-seal, sometimes you need new ones. they're not cheap, so I usually try to get the old one to seal first.