Guys,
I am an Eastern hunter of mostly whitetail and decided this year I am going to adopt your technique of packing out meat.
I have looked at a ton of game bags and am leaning towards just making my own.
Has anyone tried microfiber sheets/pillow cases as material for game bags?

One of the primary reasons for using game bags is the permeability of the bag itself.  The idea is to cool game quickly, Unless you can look at microfiber sheets and prove that they are as porous as game bags I wouldn't be so quick to use them.

One trick I've used in the past to keep flies and insects off my game is to soak the game bag in a mixture of lime or lemon juice and tabasco or cayenne, allow to dry and then pack up and use them.

Game bags aren't a once and done, buy what they call Alaska game bags, take care of them and they will last numerous hunting seasons.

I have moved on to more packable bags, but have used cheap cotton pillowcases to pack elk quarters many times.   Goodwill usually has them for a buck each.

Pepper does help keep the bugs away.

But you still have to check for eggs even with a good bag.