CEC Transport....Which one?

Looking to acquire a used CEC Transport to mate with my modified ARC DAC7.
Which one should i be looking for without breaking the bank?
Also, who in the USA repair/modify CEC products?
Thank You
I use the TL-51X which is $800 - $1000 used. I think there are a couple for sale here now.

Nick Gowan at True Sound in Northern CA is an authorized CEC service tech. RAM Technologies has some CEC mods you might be interested in looking at, but don't see why you would want to mod it.