Honestly, $175/mo for full care that also includes vet and farrier sounds too good to be true. Are they feeding quality hay & grain? Do they have a limit on how much they'll include before they charge more or make you buy your own (in case you end up with a hard keeper)? Does it include shoes on all 4 feet if that's what your horse needs (this alone can easily run $100+ each shoeing)? What if you don't like the job the farrier is doing- will they discount the board if you decide to hire your own farrier? Does the vet care include annual vaccinations, regular de-worming and fecal egg counts?
Take a look around at what it costs to board at other places in your area. If your current barn is in line with costs at other places (taking into account what services they do or don't offer) then maybe your area is just incredibly cheap. If you current barn is significantly cheaper, I'd say they're cutting corners somewhere.