So last week, I picked up a dreamcast, couple controllers, and a stack of burned games for $30 at a garage sale. Everything worked fine except the system, controllers, and everything else plastic was yellowing and coated in a thick layer of dirt and crap. It looked like someone had intentionally sprayed cola on the controllers.
I've been wanting to give my little brother a dreamcast for some time now and I figured this was a fine candidate except for the cosmetic condition. I came across an old forum post where someone had bought a vinyl skin for their dreamcast and had great results.
Here's the original thread.
Dreamcast vinyl skins? - Dreamcast-Talk.com

I took Dark's advice. Since I had a white dreamcast that was yellowing, I went ahead and got a "mostly" white background. My brother is a huge Knuckles fan. He's gone as far as to name his red dachshund "knuckles". So I decided to go with a Sonic Adventure Knuckles graphic (before the roids).

I was amazed at how easily everything went on. I never had any problems with wrinkles or bubbles, although I did have some problems with the gaps. As such, I had to make a cut here and there so that everything was symmetrical. I can definitely see what Dark was talking about though. The top parts seem to go on very clean. Once you add the sides, things fall apart. I think they just broke my graphic up into too many stickers. Overall, I think from a few feet away, this thing looks great. Just don't start looking at it too closely. I hope my brother likes it. His birthday is still a ways away.

By the way, the guys at vinyl skins shipped very quickly and the vinyl seems extremely easy to remove if you're not happy. For me, I think it was an improvement over the yellowed plastic.