For what it's worth, you have two a very active Tandem Club there in the Dallas / Fort Worth Area called, "Dallas Area Tandem Enthusiasts" or "DATES". You might want to check out their Web site: http://www.doubledates.com/
Last year's president & this year's membership coordinators are very good friends Kevin & Linda Vinson who can fill you in on what the club does and also give you some good tips on where to shop for tandems in the DFW area, as could just about any one of the other club officers. In fact, if you happen to call on Pat & Charlie say "hi" for myself & Debbie. We just spent 3 days with them at the Southern Tandem Rally in Kingsport, TN... in fact, even Don & D'Ann were at STR. Guess this means we're about due for a trip to the SouthWest Tandem Rally.
Anyway, just recognize that you have a great resource there in your local area via the members of DATES and their Web site. Heck, they even have a fairly good selection of used tandems (with photos) listed under on the classified ad page.