IAH-DAL and IAH-AUS can be had for about $108 + tax for a round-trip if purchased several weeks in advance. Service to DAL is all ExpressJet; to AUS it's mostly mainline. Both routes are less than one hour in flight (AUS is sometimes less than 30 minutes in the air) and the planes on both routes usually fly out and then right back to IAH, so you could book the first available return after your outbound flight from IAH without worries of missing it due to delays, since the return will most likely be on the same aircraft.