http://www.autometer.com/cat_accessorieslist.aspx?pid=8

http://www.summitracing.com/parts/atm-2246

Well, not $50, but still a good amount cheaper than Race-Technology.

The full sweep Autometer temp senders are about the same percentage cheaper too. I haven't used them, but I suspect they work similarly. However, at $12 for a simple 1-wire Autometer sender (#2253), step down resistors at Radio Shack are pretty cheap. Type the 4 digit Autometer # into the search box on the Summit site to get pricing (at least that is what I've done).