Dear Alan,
It is very much a lesson in free market forces, at least as the market is defined in your area (such as supply and demand), and business ethics. A viable business person, with any hope of long term survival, better factor in all the values of the stakeholders involved. Neighbors and local communities, among others, are external stakeholders to those hay sellers' businesses. Ethical business folks accept the reality their business behaviors are connected to social responsibility in the communities they live and do business in.
The loss of your business may be very well founded decision on your part. If that same decision is made by a lot of others, then some angry chickens are going to come home to roost and somebody is going to see a loss of near term profit plus loss of market for future sales. Ethics and "value added" arguements aside, if these guys do not guess it right, you are correct and will get a form of satisfaction with the ultimate outcome. They will almost certainly have a product nobody needs and little money to pay their costs - much less realize a profit. The possibility of true "price fixing" is a complaint for your state's Attorney General to respond to.
No American business (or community) is free of the causes and effects of our world econcomy. From the hay seller's perspective, a better market and profits for them may exist months down the road with someone far away. It may suck but it is a fact. It's their risk. In the meantime, you can choose to reward somebody who does business to your liking and pay accordingly.
Lastly, I agree stongly, this dead horse has probably been whipped enough. I wish you the best.