The cost will depend on the size you want. Kris just ordered a 2 1/16 Autometer gauge and he can tell you how much he paid. No mounting hardware or lines. You have to buy the gauge housing separate. If you are going with a gauge cup then mount it on the left side so it doesn't block the tach. Who cares about the gauges on the left? Autometer has both two and three gauge A-pillar pods. Those both look nice and are unobtrusive.
Winslow