English riding boots, tall boots, are pretty expensive. Have you tried looking at Dover Saddlery? They have tons. Some folks start out with rubber tall boots. They have that same trim , cool look, but in a hot climate they will be really hot.
I don't have a pair of tall boots. I wear short boots called paddock boots. Then I have a very nice pair of Ariat black half chaps (again, look at Dover) and they look very much like tall boots when they are put together.
I , would, however, love a pair of tall boots and a cousin who would buy them for me. You're a doll!