If you are willing to travel an hour from Miami, Palm Beach county has some great places.
There are a lot of different styles of riding and horses to go with it. There are stables that cater to specific styles you might like.
Here are some links. The feed and tack link will give you a broader avenue by contacting the place where they get feed. Not to mention the links.
http://wanderingtrails.com/http://tackeria.com/
