This would be the one...
http://www.racing-cars.com/pp/Manufa...W81020170.html
You want the 120A version and as Fid says above, there are plenty around second-hand inside your budget - keep an eye out. Also look out for the new G-Force from Zen Racing and a good used LRP SXX version 1 or 2. Your budget is below anything that will give you the throttle feel you need for 2WD off-road as a new speedo, but persevere on the forums or auction sites and you will come up with something soon.
Plenty of us have had years of good service from the speedos described above that we bought second-hand. HTH
