I don't know how far down into Ill. You are, but there is an awesome tack shop in southern WI (http://www.west20.com
) They are SO helpful and understanding, and they really know their stuff. They have a ton of (new) saddles, but also have many used saddles. I like that they cater more to western riders, and not just people who are showing western (they have some great show tack though too.) The owner, Julie, is the best. And she is usually there during the week. If you are going to the Illinois Horse Fair next month, they will be there! But, they only bring new saddles with when they go to expos, and a lot of them are blingy show saddles. But it wouldn't hurt to stop by and talk saddle fit with them.
Like a lot of people here said, you should look for a saddle with a wide tree, FQHB bars, 7". This saddle will accommodate the most horses. You can always pad up a saddle that's too wide, but you can't widen a saddle that's too narrow. Something to keep in mind when you're probably going to be riding a few different horses.
Because you mentioned that you want to ride reiners, I wanted to share this link with you, CALDWELL SADDLE COMPANY - The Physics of Saddlemaking
- it touches on saddle making and saddle fit/rigging at first, but in the middle they talk about reining horses and how a good reining saddle should fit. They have another page about fitting barrel horses too. I swear I've been to every website about saddle fit and this one has been the most helpful.