I stop at Goodwill about once a week for little projects, inspiration and super cheap material. I found a few vases for .99 the other day but wanted to add some color to them. I used some of the left over sample paint from the office, poured it into the vase and swirled it around. This works much better than a paint brush since it doesn't leave any brush marks.
This is a great way to add color and modernize old outdated glassware. I have also seen people spray paint the outside which I hear works just as well. I decided on paint because I wanted to keep the exterior glass to keep the shine.