As noted, you can find organic Roma tomatoes most of the year at Central Market, Whole Foods, and the like. If you are really wanting good tomatoes, do yourself the favor of waiting until the tomatoes ripen locally and obtain them from the local farmer's markets. The difference in flavor will more than make up for the wait.
FWIW. they are also pretty easy to grow in our climate, if you have the room.
4477 S Lamar Blvd Ste 100, Austin, TX 78745