I saw some cute colored bobby pins in a magazine, but they were $15 for a pack of 20. When you can buy a tub of 300 for less than $3, that's insane. Instead of paying that crazy markup, I slid some of the many bobby pins I already own flat-side up onto a card. I grabbed one old nail polish (red) and one new one (pink) and coated the pins. I left the pins and polish in the bathroom and added a coat every time I went in there.
You'll need lots of coats to get a good color, and the old polish works best. The card is important to keep the pins upright, but make sure you don't paint the pins to the card. If you end up with a lot of paint, just wiggle the pins around so they don't stick.
Voila! You saved $15 and have a new accessory for your hair.