Just bought a new boat with my first ever Mercury, Pro XS 150, SN:2B607562. I ran Icon Pro gauges on my last Evinrude which I basically stole (bought 3 gauges 2 tachs and 1 speedo and sold the 1 tach for what I paid for all three.) What is the least expensive gauge I can purchase for reliable RPM info and things like engine hours and fuel consumption. I found some that were upwards of $700 for one gauge, hopefully I looked at the wrong one because that is high. Thanks for looking.