1.	Buy your hay from a reputable dealer. You'll get more for your money with quality hay and won't waste your time returning moldy bales.
2.	Vegetable Oil in the feed is good for the hooves, and for the coat. It will also add calories to the diet for the hard keepers.
3.	Apple Cider Vinegar in the feed will add shine to the coat and repel flies from the feed bucket.
4.	Have your horses teeth checked regularly as the best feed in the world won't correct a tooth problem.
5.	If you have room for storage, buy hay in bulk.
6.	Buy feed in bulk and store in airtight containers. A broken freezer chest is a great way to store feed.  It is airtight, rodent and bug proof, and often found for free at garage sales or on craigslist.
7.	Use manufacturers coupons!  Here are some great printable coupons from Farnam
8.	Ground flax seed is cheap and will put a lovely shine on a horses coat.  It is also good for their digestive tract and their hooves.
9.	Mini alfalfa cubes make a cheap treat that almost any horse will enjoy.
10.	Muck buckets can make a very affordable water bucket. They are easy to tip over and easy to clean in addition to being affordable.