I'm currently working on a commissioned portrait puppet. I am planning on using alpine fleece or anti-pill fleece for the skin. anyone know of a good skin tone fleece that I can use? Also, which one should I use? thanks!

Puppet Pelts has a ton of skin tones. https://puppetpelts.com/

Also about Puppet Pelts is that they will dye just about any color you want and it's not that expensive for custom colors, just have the PMS # and they can get pretty close.
They are also toying around with doing custom fur blends if the demand is high enough. Lauri also told me that they are about to get in more eye selections too, so their site is definitely growing.

I was mainly asking for something more inexpensive, like polar fleece. Does anyone have a link to one?

anyone think this would work? https://www.amazon.com/Polar-Fleece-Solid-Fabric-Yard/dp/B01CUK7J9C/ref=pd_lpo_vtph_201_lp_t_3?_encoding=UTF8&psc=1&refRID=9KZ624MGQXCCW6X4C11P

It is hard to tell from just the image, but looks like it has a pretty low nape so may not hide seams as well. Color wise I think it would be fine for a dark completion on a puppet.

Polar fleece works, but the nape is not as forgiving as antron when it comes to seams and blending stitches.
Honestly though, Puppet Pelts actually have a section on their site called "Premium Skin Collection" where they have six standard skin colors that they keep in stock, ergo less expensive than their custom colors because they dye it in bulk. Most of their skin tones are $38 a yard. I use a lot of polar fleece and it works but you will find yourself having to re-pick the seams. before sewing with it, wash it on delicate and then cool air dry it if your clothes dryer has that function. That will loosen up the fibers a little more and make it a little fluffier.
https://puppetpelts.com/collections/premium-skin-collection