*$75-100 per hour is going rate around here for 'Exclusive comissioned' work with distribution rights relinquished to the client, and only able to reserve for yourself rights to self promotion.
Usually, the more rights transfer to the client, the higher the price.

Non exclusive non comissioned work where creator retains most of the copyrights and distribution rights (meaning, it can be sold again by the cretor to someone else) usually brings in less.

Aslo, one thing to consider is whether what you created is 100% your own work (models textures and all) or if there are third party items which were used, and what their usage rights are.

Freelancers should never sign over distribution rights without a contract providing them with royalties.