How much accuracy do you need? What are you trying to do?

For us, we spray, plant corn/milo/beans, and drill wheat. That pretty much covers it. If we were starting from ground zero right now knowing what we know now, I think unquestionably I'd go with an EZ-Guide 500 on WAAS with an EZ-Steer. You would be able to move this from machine to machine in about a half hour after you figured it out. You would be spending about $6500 or maybe a little less if you do some looking. You would not have to pay any subscription. It's a good way to get into things and learn. They are popular enough and enough people know about them that you shouldn't have any problem selling them if you decide it isn't for you.

I don't know anything about growing cotton. Maybe you need more precision than what a WAAS signal will provide you. In that case for closer to $10,000 you could get the same thing that could receive an OmniStarHP signal but you'd have to pay a yearly subscription of something like $1200 per year. I believe that would also be a very good value. You would probably be hard pressed to get much more of a productivity boost for less than $10,000. This setup isn't going to give you variable rate fertilizer but there may be equipment out there that you can add to this setup to accomplish this a few years from now when you're ready. If not and you want to upgrade to something way better, like I said, just sell it. Just starting somewhere and learning is incredibly valuable.