I got a Garmin 16a $400.00. 5hz receiver been using for yield and guidance with GuideMate and IPaq. This receiver is WAAS (differential correction) only this works fine in West TN although I dont know about other areas of the country. Agleader has one for about $1000.00+_- that is WAAS only. Coast Guard Correrction seems to be slightly more reliable although it will cost more $ and may not have coverage in all areas. Talk to others in your area and good harvesting.