Texas District 7 covers western Houston along with a number of Houston suburbs. Although it has long been considered a safe seat for Republicans, the district voted for Hillary (swinging from +21 for Romney in 2012) and is rated a toss up by Cook Political Report. According to opensecrets.org, this is also the house race with the highest amount raised in Texas, with 4 Democratic primary candidates raising six figures and 2 raising over $500,000. John Culberson, the long term Republican incumbent, has less cash on hand than two of his democratic opponents and has attracted a Republican primary challenger.
This market would be particularly interesting because the candidates for the Democratic ticket are mostly first time candidates with little political track record, but the race has still attracted a significant amount of media attention.