That price doesnt seem out of line to me. If your paying $175 for pasture board and then $5 a bale when she needs extra. We are paying $4.50 a bale this year for brome. 5 bucks with them tossing it to her isn't out of line. I know I'm not far from you Brandon, so the prices should be about the same for hay in your area.
My 1000 lb 8yr old eats a bale a day, plus nominal grain. My 1000 lb 5 yr old eats about 1 1/3 bales a day, plus about 6 cups grain. They are on free choice, free shelter and have enough grass for snacking on, but this time of year they are getting ready for winter here. I have always counted a bale a day 365 days for each horse I've had -- which allows for less in the summer and more in the fall and winter. My 5yr old is just a growing pig! :)
It really depends on how much the bales weigh and how much she needs to maintain her weight. My horse will eat a 50 lb bail of grass hay in 4.25 feedings (if tht makes sense) but she also gets a few lbs of grain a feeding on top of that. She is at a very healthy weight too. What type of hay is it? Grass/alfalfa...etc. I don't like alfalfa hay...way too rich.but that is just my thoughts