Hi Larry, I live in Boerne, 8b as well. As starting Chinese Elm, Cedar Elm (plenty around us), and trident maple are a few very strong forgiving trees to start with. Junipers as well, but I find that they are not as easy as some people make them to be. BTW, that Red Cedar that a lot of people love to hate here in the hill country is a Juniper, so those thrive in our climate.
Plenty of better places to get material from other than ebay. Check out evergreengardenworks.com, internationalbonsai.com, kaedebonsai-en.com to mention a few. Also, a lot of members here sell as well, and I think also the 99cent FB auctions. I haven't done the FB one yet, so I don't know how much would be available to our area.