Many people probably knows this but making your own primer is waaaaaay cheaper and easier than buying primers at stores or drugstores.
The ingredients are: liquid foundation or concealer that matches your skin (i used my sister's since i don't use foundation/concealer, by the way she's got an account too, check it out: drwhofan92) and white body butter (can be scented or unscented, i use cocoa butter), and a small mini jar of some sort.
All you do is mix the concealer/foundation together until you think is good! You can add shimmer powder for a shimmery base, too.