I have 2 eyeshadow primers.
1.) I had a demo at MAC and I asked to buy what he used to make the colors look good, I walked out with a little tube of MAC Paints in Bare Canvas for $16.50. Oh my, just now as I'm adding the link I see that this is described as a champagne color with shimmer. For the record, I have never seen any shimmer in mine.
2.) In august, when Tarte was having a 40% off sale I picked up their Lifted primer since I wanted to play around with different brands. I also got their wonderful lip stain (more on that later).
I know those aren't the standards, all the gurus and beauty bloggers seem to suggest Urban Decay Primer Potion or Too Faced Shadow Insurance. Well, I of course looked at those two when I first learned about how you need primer to make eyeshadow not suck. They both have talc in them and a lanolin derivative. I'm not going to tell you I'm the perfect vegan and have exclusively vegan products, I don't, I allow beeswax and sometimes even carmine, but I draw the line at lanolin because I think it's ickier. Mainly though, it's the talc that is a sticking point, I won't buy anything with talc in it.
1.) I like this, I like it a lot. My appreciation for what it can do may be colored by the fact that it's my first primer, so it seems like a miracle product. I'm not really fond of the tube it comes in though, has a nasty habit of oozing out way, way more than you need, so you end up wasting a lot. The $16.50 vs $18 for either UDPP or TFSI was another good reason to go this route, but honestly still seems too pricey to a poor and frugal me.
2.) This is a great primer- grips my shadows, keeps them from creasing or fading, and makes them look better overall. No talc or petrochemicals and it's vegan! Also, I think (or hope) Tarte is a little less planet-raping than the majority of cosmetics manufacturers (or anything manufacturers), on account of the fact that the packaging is biodegradable. It is fairly difficult to wash off, but I gather that's kinda universal with primers, and it may be I'm just using a lousy makeup remover. This is regularly $20, which is too much for me, yay sales!
About the supposed firming benefits... I haven't noticed any.
I would suggest either of these as products that get the job done. But I wouldn't recommend buying them unless there's a sale or some kind of deal.
The primer from Concrete Minerals seems like a good one too, I might have to try it. If it works as well as it's ingredients suggest it should, it's the best deal on primer at only $8.99!
Hopefully this was informative for some people.
If you know of a super fantastic primer I should check out, let me know!