Eli,
I found two internet vendors that I would consider.
First is grapevinesgalore. They will sell relatively small quantities at very reasonable prices. If you browse the variety/rootstock combination that is right for your soil they were most likely to carry or be able to get what I was after.
Second is harvest express. They're more pricey. They also can get you varieties not listed directly on their web page. Just ask. They were incredibly responsive. They also, for what it is worth, provide a guarantee on their vines.
As you're in Texas I would recommend a book I picked up to help my research. It is Growing Grapes in Texas by Jim Kamas. I found it an excellent reference.
Best of luck.