One of my favorite things to do is go on polish hunts and the nice things about polish hunts are bargain bins. If you're patient enough, you can find recent past collections for half off or more but you'll have to sort through endless bottles of crackle polishes! Seriously, who keeps making this stuff?
I picked up OPI My Scales Walls from last year's Spiderman release and I added some blue rhinestones.
I'm always looking for a good white creme that applies well to use for french tips or a base for nail art. OPI's My Boyfriend Scales Walls is an off-white with a hint of grey so it isn't so blaring white. It applied a little streaky at the first coat and was completely even within two coats. I added two coats of top coat to get the rhinestones to stick on. They were super stuck on and took forever to get remove!