I would pass on anything with really high withers. I have a gelding with high withers and he's a pain in the butt to fit a saddle to. It's nice that the saddle doesn't move, but I've always had a MUCH easier time finding saddles for low withered "round" horses.
I like the appy mare, but definitely take a look and see! 14 is a perfect age for what you want to do. Also, as others mentioned, don't fall in love at first sight. Go back and look at the horse a few times before deciding on anything. If they have that many horses, and so many that are for sale, it may be possible that they are horse traders. There's nothing wrong with getting a horse from a trader (I've had a few excellent and well priced horses from them) but traders are like car salesmen. They know all the tricks! So if that's the case (I'm not saying it will be, but just be wary!) don't let them pressure you into anything.
I like the appy mare, but definitely take a look and see! 14 is a perfect age for what you want to do. Also, as others mentioned, don't fall in love at first sight. Go back and look at the horse a few times before deciding on anything. If they have that many horses, and so many that are for sale, it may be possible that they are horse traders. There's nothing wrong with getting a horse from a trader (I've had a few excellent and well priced horses from them) but traders are like car salesmen. They know all the tricks! So if that's the case (I'm not saying it will be, but just be wary!) don't let them pressure you into anything.