This isn't a template source, but I recently learned a trick with CL posting. Here is an example of a post I made:

http://stgeorge.craigslist.org/bfs/811112253.html

To do this you'd either need to know html (which I don't) or have a good software program for creating web pages. I have Dreamweaver, which allows me to create the page in design mode (graphical interface), then switch to html view - which lists the html code. So...I created the graphic you see linked above as a web page, and uploaded the page to my server. Then I copied the code from Dreamweaver and pasted it into the post area of Craigslist. (I make this sound harder than it really is!)

The benefit - I have full control of what I put up, I can change it at will - and I don't have to pay anyone to do it for me. The down side ... you have to have a website and software that lets you view and copy code after creating it.

Hope this helps...