How much would it cost for an intellectual property contract?

I'm wanting to currently creating my own video game. I have not registered for a company yet, so everything will be in my personal name until then. I am wanting to contract artists on Fiverr. I have found two contracts that I think might work with a bit of modification to them. I know that Fiverr has their own terms of service that address ownership rights, but the way that they handle ownership with their commercial use license seems misleading. I want to ensure that I have full copyright, trademark, licensing rights of all kinds on any works purchased through Fiverr. How much would it cost for an intellectual property contract? Would it be cheaper to modify the current contracts that I have instead of creating them from scratch?