It's a supply and demand thing. More demand than supply and prices go up. Plus, as in everything nowadays, cost of production goes up constantly. Farm machinery runs on fuel. Fuel prices have skyrocketed. If you don't get it straight off the field at harvest time, you also pay for storage. Farmers can't afford to play around with their assets.
As SR says, some hay suppliers certainly take advantage.
In my case, I can't even find pasture hay or roundbales. Only small squares of alfalfa, oat, 3-way. I get orchard/timothy hay from the feedstore, for 21$ for a 85lbs bale. It's coming from Oregon, so trucking it in is included in the price. Drought affects us here, too, even tho most hay comes from irrigated fields. But irrigation costs money.
So I don't blame the producer for higher prices, unless it's really bad hay which shouldn't be sold as horse hay