If you can't find the color of nail polish you want, why don't you just make your own?
Step 1: Supplies
All you need:
1) Food Coloring (the kind that comes out in drops is easiest to use)
2) Tooth Picks (Bamboo sticks for shish kabobs also work really well)
3) White Nail Polish (light colors also work)
Step 2: Adding Colors
It is best to do this in a bottle of nail polish that has been used a few times so it doesn't over flow when you add the food coloring or the tooth pick.
Add the food coloring directly to the bottle of nail polish. Sometimes it can pool up at the top and not sink. If it does this you can stick a tooth pick in, and it will help move the food coloring around.
Step 3: Stir
Use the tooth pick to stir the food coloring in. You don't HAVE to do this, but it makes it a little easier in the next step.
Step 4: Shake
Put the lid on the polish and shake it up. The little ball inside helps mix the food coloring in better than the tooth pick, but after a minute or so of shaking it starts to make my arm hurt( I guess I know how those SHAKE WEIGHTS work now).
Step 5: Rinse and Repeat
Check to see of the color is what you want. You can always add more food coloring, but you can't take any back. If the color is good, you're done. If not, go back to the beginning and mix more in.
Step 6: Paint
To use this polish, make sure you use a clear base coat first. Some people do this all the time any way, and some people (me) figure eh, why bother. If you use a lot of food coloring, or if you don't mix it well, the food coloring can stain your nails. If it does you can just use nail polish to paint over it, but a clear base coat will keep it from staining.
Step 7: Also Try
This would be fun to do at a slumber party or in school colors for spirit week. You can take it a step further and make labels for the bottle (which I was planning on doing) with mini address labels. If you want a custom glittery polish, you can add very fine glitter, or embossing glitter to clear polish.
I made 2 polishes, the minty green is made with 15 drops of green food coloring and 10 drops of yellow. A also used the rest of the bottle of yellow food coloring to make ... yellow polish you'd think, but it came out a little orange.