Yeah there are people with over 100 trade tickets so I don't think they max out.
I'm kind of sick of the royal exchange dictating the way I play the game and constantly having to collect from animals. I have all my permits and my chateau upgraded to level 5 and have lost motivation to keep the exchange running constantly. I guess the next goal is to collect enough tickets to trade them in for royal and enchanted supplies to see what they give and so I will have completed at least one of each trade.