I didnt want a cartoon car or animal or anything, I wanted relatively simple text with some "bubbles" so I just did my own. Nice font (ie easy to read), red letters with a black border on each letter.
I used corel, but you could use photoshop or any other graphics tools. I saved several versions of it - a t-shirt version, signs, website, letterhead, etc; each is a little bit different. Also saved it as a vector, jpg, and png for various purposes.
If I wanted more complicated I'd have used a local graphics guy, he charges by the hour for that kind of work.
edit: In case you are going to ask, here is the local graphics guy. I dont know how busy he is currently.
http://graphicsonthego.com