how do i find the value of old coins?

I hav a load of old coins, but i want to find out how much each of them cost, does anyone know a website in which i can find their price easily? I already tried ebay I already tried ebay, i dont wana know wat other people sell em for, i want to know market price

I have an old korean coin dating back to world war 2. Does anyone know where I can look to find an estimated value for it? I have tried looking online and am only finding websites that list US coin prices, so if anyone knows of a site, or a physical shop in Arizona hat I can visit I would greatly appreciate the help.

Me and my dad are coin collectors and we sell coins as well