Your $100 budget is going to be difficult if you want to go the custom route. $100 doesn't buy as much knife as it used to.

I have been a fan of the Buck Vanguard for a while. I think the ergos are really good for big game skinning and processing tasks. Buck does a good job with their heat treat and probably gets as much performance out of their 420 steel as anyone can. If you can add just a little to your budget, you may consider the Cabelas Alaskan Guide Series version of this knife which uses S30V steel for $120. The coating and logo turn off some folks though.

https://www.cabelas.com/shop/en/cabelas-alaskan-guide-series-xxx-knife-by-buck-knives-100815873


As far as customs, you may get lucky and find a deal if you keep an eye on the classifieds.

You may want to try reaching out to Michiganroadkill here and see if he has something ready for assembly or already built but not spoken for. Don't expect to find something with him for $100 but it would give you an idea of what your idea of features and wants may cost when you start planning your build. His prices are often very reasonable and you get a tremendous bang for your dollar.