Gunshop.
in excise RG-23 PART 1 AND RG-23 PART -2 ARE REGISTERS TO BE MAINTAINED BY ASSESSEE
50-100
In perfect condition the Rohm RG 23 .22 cal runs from 50-75$ hope that helps
Try gun shops, gun shows, want ads, on line auctions.
25-75
About $50. Low quality, low value pistols
No known sn data published.
Rohm. See link below.
25 USD
No serial number data base. Most of these were from the 1960s
10-30 USD or so
Best left to a gunsmith.