The pellets sound about right for a month.
Assuming normal sized, decently tight bales of hay, I would think one per month would be fine. However, if you have a good storage spot for it, I would get what I could when I found it. Maybe it's a function of the crazy weather the last two years, and the fact that it seems a LOT of people are raising cattle right now. but I have seen a lot of people, including me, looking for hay and not finding any.
The BOSS, assuming you aren't also feeding birds, will likely last you a while. Again, that's fine, as I also buy in 50 pound bags as they are cheaper. Get yourself a nice heavy duty lidded garbage can to store it in. But I wouldn't count that as a monthly expense.