re: How much am I gonna regret buying one of these little mini ATVs?

Look for a used reliable brand..

That or completely take that thing apart and rebuild it torquing everything properly and putting loctite on anything that needs to stay put.

Have dealt with a lot of chinese pit bikes, they just fall apart if you don't go over every bolt with a fine tooth comb. Be prepared for the motor to give out fairly easily as well.