used digital slr bodies

Hi all,

I am shopping around for a digital SLR. I may wait till fall and see what 
the new models are, but I am considering picking up a used body to get me 
started ... eventually I want a camera in the Canon 5D category, but may 
consider something less to get started.

I purchased camera gear from eBay in the past, I have some Contax lenses 
for my Aria and a Mamiya TLR that I have been happy with, but I am much 
more wary of purchasing a digital camera from eBay because I am more 
concerned about the condition of the digital sensor. It seems to me that 
the mechanical film cameras seemed more bulletproof.

Any thoughts or experiences purchasing used digital bodies?
Anything to look for?

Steve