Welcome to Houston. In order to help, I'd need a bit more information. As to your half-hour requirement, are you referring to the time it takes to get to work during the traditional rush hour? If so, your choices will be a bit limited. As diverse and vibrant a city as Houston is, the infrastructure is essentially a freshman civil engineering project gone bad. We've got a light rail system that serves downtown from several areas, with four more routes under construction. If this option would work for you, you're going to have a considerably greater selection ... we have several park-and-ride facilities that many residents find convenient.
Given your price point, I'd concentrate on a single-family home ... duplexes and triplexes aren't all that common in the more in-demand areas. $200,000 can buy you a great property if you're willing to be a bit flexible ... i.e. a "better" location and a home that needs a bit of updating vs. one that's more recently built, but a bit longer commute. That $200,000 would buy you a gorgeous 3,000 sq. ft. completely updated home further out, while the best you'd do would be an older (probably 50 or 60 years) 1500 sq. ft. property closer in ... of course, there are varying degrees within those parameters.
Your best plan of action would be to see what your money will buy in several locations. With a combined forty years in real estate, my wife (a lifelong resident) and I have welcomed dozens of new Houstonians, and taken the time to acclimate them to their surrounds. It will be our pleasure to work with you. Please get in touch, so that we may begin this exciting journey. I look forward to hearing you.