There are two types of tachs, one is 4-terminals (+ light - so 5 wires needed) and one has a canon connector. I believe that signals are the same in both cases. In the past the ones with the canon connectors have been less expensive because they require the special connector you might have there?
But the easier to source 4-wire should be fine as well. The 5-wire requires power, ground, tach +, tach -, and illumination lights. (Power should be applied only when the engine is running.)
The one I installed in my rig (not canon) came from SecoParts. Looks like the price has jumped a bit in the last year, but may be cheaper then ebay. (I'm not affiliated with seco in anyway, just bought from them in the past.)