I don't have any tack shops around here, either. Well, we do but they're for the rich folks. lol (and even though the prices are through the roof, the tack is so shoddy!!). Besides, with the internet, you can get better price deals on the name brands, or even slightly used. "Retail" pricing is a joke anymore, but you take the risk in the saddle not fitting (which you're going to do anyways unless you haul the horse to the shop with you. lol)
My daughter started riding when she was 5. She's 6 now and she's a LITTLE girl. She only weighs 40 pounds and she's short. (she's a gymnast, so it's perfect for her). I sat her in my old kiddie saddle. She was absolutely swimming in the seat, so I had to find her one she fit in.
...the problem, though, is that she rode a foundation stock Morgan - with the big rain barrel belly and the monster neck. Plus, to make matters worse, she insisted that her saddle be hot pink to match her bridle and breast collar (and pad, boots, and helmet cover) - and I didn't want to spend a lot of money on it cuz she'll outgrow it in a few years. The biggest problem I ran into was finding a tiny seat on a saddle for a full-sized (and then some lol) horse. She takes a 10" seat and still has room to grow. What a mess!!
These companies don't realize that not every kid rides a pony. Tiny little girls DO ride giant horses (and do just fine). I went through 4 saddles before I found one with a seat that fit her and a tree that fit him!...and I even found it in hot pink. =D
(I made the money back though...sold them on Ebay and actually made more money on each one than I had spent) ;^)