Herter's imported revolvers made by Sauer & Sohn in West Germany. Try http://www.e-gunparts.com for parts.
$100-$150
http://www.gunpartscorp.com/forum/
Numrich gun parts
Herters was an importer headquartered in Minnesota from the early 1960's to 1979. The guns they imported were of good quality but strictly valued as shooters. I'd suggest you check one of the chain sporting goods stores like Dicks or Garts or Gander Mountain for the cheapest NEW .22 revolver and figure yours is worth about 2/3 as much if it is like new, 1/2 if worn but functional or nothing if it's rusted and broken.
If your local gun dealer cannot help, contact gunpartscorp.com. They have SOME parts for handguns imported by FIE.
$100-$125
5-50 usd
I have a marlin little joker i will sell for parts
Parts for an H and R Sportsman Top Break 9 shot 22 cal single action revolver can be found in many ways. The internet, especially gun websites, sell parts for different guns. Also, gun shops can provide certain parts for this type of gun. Calling in advance to find if parts are in stock would be best.
You can find out how old an HS Model 10 22 revolver is by taking it to a local pawn shop or gun dealer. You can also use publications that are written to help identify the age of a revolver.
Where can I get parts for a schmidt ostheim rhoen 22 revolver hs121s /hs69
Many are