blown one out already Frank? Don't let BBQ Bob hear... :-)
It kind of depends on which harp. If it's one of your big rivers, just keep it as a practice junker. You are going to knacker a few harps learning how to replace reeds. Best place to get new reeds is to keep your dead harps in a box and wait till you have a donor reed that fits.
You could try contacting Hohner USA I guess.
Personally I'd just get a new harp, or new reedplates until you have a good collection of test patients to practise your open-harp surgery on.
Phew! that'll keep Bob off your back a while then - if he ever finds out you're blowing too hard... [shudder]
(sorry Bob - couldn't resist!)
Most people either reuse the rivets from the donor reed, or get some really small machine screws.
If its your Suzuki that goes, then you need to check out one of Brendan Power's videos, because Suzuki reeds are spot welded, not rivetted. It's still possible to replace them and Brendan's is the best (only?) info on welded reeds.
Not all reeds are suitable. Hohner may use different sizes to Seydel for instance. There are also likely to be dimension differences between different models from the same brand, so check before you buy. I guess guys like Harpwrench and Buddha can advise on what is compatible with what.
Actually, it's not harder to replace welded reeds than it is to replace riveted reeds. Actually, it's probably a little easier because you don't need a special reed de-riveting tool. View the following video for tips.