Hello everyone, I am new to this forum.
Without knowing your exact location and what other barns charge, we really can't say. Here in Pa, I wouldn't board at a barn that only charged $500. Most decent barns start closer to $700 and go way up from there. My barn charges full training board of almost $2000 per month.
Where I am from in NC, the average full board goes for $400 and a friends farm in Califorinia starts at $600 and goes up from there.
I guess what I am saying is, do some research and find out what the other barns are charging in your area. Start with the phone book or the internet and call around asking general questions about what they offer and finally what they charge. If you want, ask questions as if you are a new boarder to the area and play dumb.
Only local research will tell you if $500 is the right number for your area.
Hope that helps. Good luck.