It's actually totally dependent upon where you're located. Here in the Atlanta area, it's very common to find the amenities you have for an average of $600 a month. There are a few places where you can find it for $450 to 550, and quite a few more where you can find it for $800 to $1200 a month.
Now, you're probably thinking, that's crazy! Well, let's take property taxes as just one example. My wife's family owns a 270 acre tract 45 minutes north of Atlanta that the property taxes run around $2700 a year on. Go just 30 minutes south to where we're at and it's quite a bit more expensive. We're currently looking for a larger farm (we're on 5 acres at the moment) but I have to keep the county lines and taxes in mind to figure into our costs. There's a 13 acre farm we absolutely love right down the road in the city of Milton, Fulton County. Wanna take a guess as to how much taxes on it are? $5910 per year, which comes out to $454 per acre. Now, I don't know what your taxes are on your 84 acres, but I'd be willing to wager that they're a good bit less than $38k per year, right? (That's $454 per acre for 84 acres.) We have to figure that $500 average monthly tax payment into our fees that we charge for boarding. (You also have to take into account that the county where that farm is has an ordinance that allows a maximum of one horse per acre. So if we own two horses ourselves, we can only board 11. That's $45 a month per boarded horse that we have to charge just to cover our property taxes.)
Anyhow, good luck with your new facility! We wish you all the best!