That's all I sell and I'm about to run out with a list of customers who want it but won't have enough for. Same acreage. The key is to keep your prices fair, get some long term customers with older horses (10 - 15 y.o.). I joke that I sell baled weeds.
I take a later first cutting (mid July) when I know I have 3 - 4 days of drying. The crisp hay bales nicely. I use a stack wagon to pick it up and customer help to take it away and/or help put it in the mow. This way it stays dry, green tasty and smells wonderful. $2.50 a bale, $2.00 if you help. $4.00 if I have to deliver it.
No fertilizer. Tractor and equipment is paid for, just diesel. As far as I'm concerned, it's free money. I use an accountant to run my taxes on the 'farm'. A few bucks for occasional parts. This year's expense is a brand new Miller 211 for farm repairs. County keeps my tax status as agricultural.
Well worth it IMHO. Once you get a Vet doctor to comment on how good your grass hay is for somebody's horse, the stuff flies out of the barn. BTW, a primo 2nd cutting can be done Septemberish and a few top quality bales for the very old horse with poor teeth can pull $4.00 a bale