I painted mine a few weeks ago after watching some vids and asking around. I ended up going to Walmart and buying a cheap tube ($2-$3) of black water based acrylic craft paint. I did three coats using a decent quality sponge roller and used a hair dryer between coats to make it dry quickly. I'm more than happy with the results.
Also with this kind of paint, if you get tired of it; it will scrape off very easily using a straight razed.