Good Luck
I looked for one for quite awhile. Despite several 'I'll get back to you's from the '4 sale/wanted' board, I ended up with nada.
Have you considered the Panoram (avail at rocky mountain among others I'm sure)? It's a computer..has all the basic stuff...max mph, avg mph, total miles traveled etc etc.
I finally did get an odo. Some kind, gracious, conscientious individual put the miles back in my smiles.
Thanks dan!!