Fun to decipher the marks on Belgian guns, and happy to help.
It's going to be next to impossible to find the sale price of a comparable Ronge, which was a respected maker.
Here's one that sold 20 years ago; much rougher and lower quality but fluid steel
https://www.gunauction.com/buy/6567716
The concern of course is what 'inexpert' gunsmithing has been inflicted on the gun in the past, as evidenced by the top lever screw, and if the barrels are free of defects. The cost of refurbishing the gun may exceed its value.
Threaded Mode