Well in my area (Phoenix, AZ US) boarding runs from $250/month to $400/month. I didn't see anything outside of that range when checking around. Usually that price includes hay and feeding twice a day and once daily stall cleaning with fresh shavings 1-2x per week.
I haven't bought my own hay so haven't noticed prices.
Prices vary a lot between our Walmart and the smaller stores.
A 40# bag of Purina Equine Senior is $18.99 at my local Pet Club. Triple Crown Senior is $21.99. A 60# bag of beet pulp pellets is about $15. Bag of BOSS is $20 there but $15 at Walmart.
Rubber feed pan at Wal-Mart was $4 and $12 at Pet Club.
Bag of treats by Manna Pro is $12 at the Pet Club and only $7 at Wal-Mart.
Manna Pro's Vitality Supplement is $12 at WM and $25 at Pet Club.
I buy a lot of my stuff online because of lower prices. The Hamilton halter I just bought was $35 at Pet Club but $20-ish on Amazon. The lead was $15 at the store and $9 online.
All of the tack (head stalls, bits, pads, halters, etc.) at the feed store seems to be close to twice as expensive as online, which is a bummer because I love to support local businesses but I also can't justify spending that much more right now.
I ordered supplements online because they were approx, 30% less than in the store plus I don't have to pay sales tax if I ordered from out of state. (At least not now...)
I plan to purchase a set four SMBs that is $65 online...at the local stores they are approx. $160. Again, plus tax. Our sales tax is close to 10% so it adds up fast!
Um, what else have I bought in the past two weeks since I got my new horse? :) A lunging whip for $15 at the local store.
Brushes and other grooming supplies...$2 for basic hoof pick, $7 for dandy brush, $9 for one of the nicer curries, $5 for mane/tail brush (it's similar to a human brush), $5 for curry glove.
I bought my shampoo and conditioner at Walmart for $5/32oz vs. the feed store's $9-12 per 32oz.
Fly spray also is much cheaper at Walmart or even the hardware store.
Bought a Supermask 2 flymask locally for $17.99 but it's $12-ish on Amazon and other online sources.