We had a lot to learn about hay it seems. Those seemingly similar round bales are actually quite different than one another.
Round bales are measured in feet- in our area a 4 foot round is the preferred choice. While square bales do pack into a barn more readily, round bales tend to last longer as they are packed tighter.
The makeup of hay greatly increases it's value. Timothy hay with a mix of clover, alfalfa and leguemes being the prefered choice. Straw, the leftover stalk of a grain, is worth less but is useful for bedding and cheap feed.
So how much is hay worth? In our area a 4 foot round bale brings about $30 - our 48 acres gives us about 50 round bales, seems like a lot of work for $1500! However it's valuable feed for livestock.