Santa...I think both the Garmin Plotters and Radar are excellent products. You do have the ability to add virtually any auto pilot brand and interface through the NMEA protocol. With a 31ft. IP you may be thinking of a wheel pilot rather than under deck and in that case the RM SP1 (about $1100) is the only thing available. If you are looking for an under-deck model...suggest you look at the Simrad lineup.
Also...please give the sailnet store a look before buying elsewhere. They are usually quite competitive and in these tough times...it is good to support the folks who make this board possible IF they can meet your needs competitively.
No longer posting. Reach me by PM!