I'm not quite sure which way to go on this one. Ordinarily I'd say a 73 win team with as many holes as the Astros shouldn't be dealing the farm for a slightly past prime player. In this case, however, there are two mitigating factors. First they play in the NL Central, where not crashing the team plane makes you a legitimate contender. Second they are sort of pot committed at this point. Rightly or wrongly, they have spent big bucks locking up Oswalt, Berkman, and Lee for the next several years. They almost can't afford not to try to maximize the value of those deals.
Apologies for the fence riding. This is a toughie.