Also the PNW, and honestly… you got it good. Indoor anything is going to pop you over $400 regardless of the other amenities or “amenities.” You didn’t mention barn, shelter, tack room, etc? A woman on the island charges $500 for a stall and a 12xwhatever (depends) run out, usually like 40’, because she has a covered arena. Said cover though is so danged high that wind and rain can blow in easily, the “walls” are about knee high so good luck keeping a horse inside if it wants out, and only part of the arena is covered, so the footing is wonky because the ends get rain and the center doesn’t. Or you can put your horse in a small muddy turnout with a shelter if the runouts are too small for your tastes. Another barn only offers small paddocks (40x40 to 40x100) with a shelter but has a huge outdoor arena with professional footing and an extra large indoor arena with professional footing. Both barns supply hay. Second barn, not sure what they charge but probably $400+ and owner has to muck the paddocks.
There is a place right outside the city limits with iffy fencing on a busy road that is pasture board (literally no other amenities, I do think there is storage for hay/feed? and a water hose) for like $100/mo or something, but it’s also a self-care situation. Doubt there is insurance of any sort and if you want to ride you are doing so in the heavily treed pasture with other horses. So pick yer poison.
All of my examples are mid- to low-end examples. Other barns charge way way more. One barn charged $585 when I inquired back in 2007. Others are $500 to $750 that I know of off the top of my head, generally with hands off BOs/BMs, without covered/indoor arenas.