Yea so that link azzeffir posted is relevant. Also see
here under the big green "2) Duels and clan wars rules"
Specific point of interest to you:
1. Wagers must be verifiably owned quantities which can be legitimately transferred between the two players. (Textures cannot be verifiably owned as of yet, nor can USD or other forms of "real" currency. One cannot use duelling as a basis to transfer qi, or bypass qi or other trade restrictions on items.)
So yea anything that involves currency or w/e outside of Toribash is really really encouraged against. We don't have any control over it and staff have no obligation to deal with it. That said, don't take it as an invitation to go trying to usd duel scam people. We'll ban you all the same but if you're on the other side you'll be getting no service from us.