Looking for an "user trades" plugin

Hello together!

My name is Adriano and I am the owner of a Brazilian Krosmaster (game) forum.
http://ligakros.com.br/

Now I would like to have a place for all users that they could buy/sell/trade their own miniatures.

Most of users are players and buy/trade several times because they change their teams frequently.

I appreciate your help. Thanks in advance!