@Pierre Alexandre Lidji there used to be a section here called the FilePlace that had various contracts and forms. I cant find it not but you may find it with a search. Sometimes the quality of these contracts can be suspect.
As important as having a contract that is "Legal", is having one that says what you want it to and that you understand. It is worth taking some time learning about contracts. You will use them a lot in this business.
There isn't a standard "wholesale contract" and many wholesale contracts I have seen are not legally binding contracts. If you want a contract to protect you, you should talk to an attorney. If you are trying to skip this process and avoid paying fees I would recommend you start networking locally and develop a relationship with a wholesaler. There are some good wholesalers but others seem to have no idea what they are doing and end up leaving the business quickly.