How much would this maxed go for?

Given you have no reputation you'd have a very hard time selling that account. If you did manage to find a buyer, it wouldn't be worth as much as you're probably hoping as Rs3 accounts aren't too in demand. Unless you find someone that is specifically looking for accounts with 120s or high total xp, you'd be lucky to get more than a few hundred $ - Maxed accounts are quite easy to find.

The biggest issue is that people will only pay as much as they're comfortable trusting you with, which as a newcomer is very little.