If a person selling hay figures out how much they've got in field maintenance, fertilizer, fuel, equipment, and labor, they're hay will be expensive.
For years, around here, a large roll 5x5 or larger, would go for around 20 to 25$ a roll. My uncle figured he had half that much in fertilizer costs alone, and with fuel and maintenance costs added, he wasn't making any money if he sold any hay. He sold excess in small quantities to neighbors and relatives when they ran short.....more of a public relations/good neighbor policy, instead of making money.
Last summer, there was zero hay cut. Nada. A roll of road weeds was bringing 80$/roll. Corn stalks trucked down from Dallas was 85$ + shipping.
Most herds locally were drastically pruned. The price of cattle plummeted locally.
So, rambling over, back to OP's query. Unless you like to work real hard and have lots of money to give away, hay making, selling, and hauling, is a risky endeavour. If you figure up how much it costs to develop and maintain a meadow, the fertilizer cost (unfertilized hay is just belly filler), the fuel costs, the hauling, the labor!, there's not much money in it.
Now if a person could figure out how to sell futures on the Chicago Board of Trade........you'd get rich!!!!! The only folks who get rich in farming are the traders, in their starched shirts, with clean fingernails, that never ever smell diesel on their clothes, or get grease stains.......but I digress...
Good luck, and if you jump in, keep you're eyes wide open! Oh, and buy some tarps..... cause I (and I'm sure every one else here) wouldn't buy wet hay.