You may or may not be aware that there are manufacturers who make generic products that companies buy, stick their labels on and then sell. These products often have the same or similar packaging, they almost always have the same product name and shade name and they always have the same ingredients. Unsurprisingly they have very different price points.
I discovered this a while ago when I bought a plumping lip gloss for $65. Huge price I know, but people raved about it and it was back when I didn't buy many beauty products so thought it was worth the splurge. You can imagine how annoyed I was when I googled it and found that I could have bought exactly the same lip plumper for $18!
If you want to research this search Micro Bubble Lipstick, Lip Tox and Liquid Powder Mineral Foundation. See what I mean? Lots of different price ranges for exactly the same product. So if you find a product that you love, google it to make sure you can't get the same thing cheaper elsewhere.
Sarah from The Science of Beauty has done this post about two identical primers with very different price points. It's well worth a read.