Does anyone know what the best auto steer/mapping system for the money would be for a JD 9750 STS?

We use a brown box for steering ( you will need the auto track keycard installed) , a John Deere 3000 globe on the SF1 signal, and a John Deere ATU steering system. We use it only for combining soybeans and run at angle to the rows. It works awesome !! We have a Case IH EZ steer system on a tractor for tilliage however it is not as consistant as the John Deere system in our combine. We purchase the Deere system for $4000. We have about $3200 in the Case IH.