For a full, 3D avatar, take a look at this:
https://steamhost.cn/steamcommunity_com/app/274920/discussions/6/487877107146081606/
This gives you an indication in what price-range you will have to look.

For a 2D avatar, which does use an extra DLC, you will have to find an artist willing to draw the image for you in the correct layers and either rig it or you would have to rig it yourself (to save costs).
In this thread here is someone who just made a screen-capture from them rigging up an avatar from the image they've drawn in Photoshop (although other programs might work)
https://steamhost.cn/steamcommunity_com/app/274920/discussions/8/451848855005706161/

2d/3d artist here. expect to be paying 500-1000 dollars for an avatar.