If you can't afford the Incra, I vote that you look on Ebay for an old
Delta/Rocwell mitre gauges. The problem with the gauge you link to, is
that the pointer is never accurate. You'll end up having to realign it
with a square or drafting triangle every time to adjust it. Doable,
but a inconvience.
The Incra is very good! I have one, however the sliding stop on it is
somewhat painfull to move around, but once you zero in the measurement
tape, it can be very accurate for cutoffs.