Shop Truck Signs.....How??

[Raymo]

Looked through the "shop truck" pics here. Lots of nice signs on them and some real creativity! I'd like to get a sign on my door, but here's the problem. I'm not an artist. What kind of simple computer software do you use to do a layout. You know, some nice fonts and designs? Getting it on the truck will be easy, as I've seen a pounce wheel, paper, and powder used.
There are various sign making software out there but it's expensive for a 1 or 2 time use. I just want to be able to print something off my HP and Mac. Any ideas?

Thanks
Raymo