Hi I'm not sure what you are refering to, this is a programming part or the visual part.
For commissions you should ask for the standard and no lower just because in your country you can live with X amount of $, you have to think is better for you to ask for the standard and is better for the rest that you ask for the standard price.
Depends on the skill that is needed, you won't get a complete project, you will get tasks to do, or fixing errors (assuming you are in the programming part of gamedev)
I work in visuals but you should always do a research by your own, try reddit on r/gamedevClassified or something like that, you will get a hint of how much people is asking for your knowlege.