@galen84basc -- Don't worry, a lot of people have the same problem you do. There are actually several good ways that you can use for nail polish stain removal from fingernails and toenails, and best of all, they're all cheap!
OK, so your first step is to soak your fingernails sans polish in warm water that has some dishwashing soap in it.
After that, take a terrycloth washcloth and gently buff the nails dry. Then take an old toothbrush and gently scrub the surface of your nails with that. Finally, you can take some hydrogen peroxide and use it like you would nail polish remover.
If that didn't take care of it, you've still got a few more options. The first one is my personal favorite since it makes your fingers smell nice -- you take a little bit of whitening toothpaste and basically brush your fingernails with it.
You can also try rubbing the nails with lemon juice or bleach, but both of these methods are very harsh on your nails and your skin, so I would only recommend it as a last resort.
You can help prevent stains on your nails by using a base coat before you paint, or using lighter colors -- darker colors do tend to stain nails, as you've noticed.