I'm thinking there must be a way to prevent commas from being entered into the SB trade box.

Well, it happens for other things, why not here too? this will it'll prevent people who did not know about the comma thing from happening.

and for those who don't know and are reading this (unlikely) if you put a comma between two numbers in the trade box for sbs or gbs, it'll only count the first number(s) and not the numbers after the comma. and that can be really annoying when you're so used to putting in commas in your numbers. If we prevent the commas from ever being placed in the trade box, then this won't happen.