In both cases, the tradeoff is the same - drive fifteen minutes to save twenty bucks - but people were much more willing to do it for the cheap item, because $20 was a higher percentage of its total cost. With the $2000 TV, the $20 vanishes into the total cost like a drop in the ocean and seems insignificant.

Evaluating cost savings as a percentage actually makes a certain amount of sense when evaluating policies rather than acts. Cheaper purchases tend to be much more frequent: you probably buy many more shirts than you do big-screen TVs, so expending the effort to find the cheapest source of shirts and evaluate whether it's worthwhile to go out of your way to buy them will save you several times $20 over the lifetime of the policy, whereas the TV is effectively a one-time decision which will only save you $20 total. True, the 15 minute drive time is per-purchase rather than per-policy, but 1) the cost is not just the drive time, but also the effort to research options and the cognitive load of picking and option, which are one-time costs, and 2) a general policy of thriftiness for small, frequent purchases can have a substantial effect on your overall financial situation, but indulging in overpayment for convenience on the odd big one-time purchase is an affordable luxury.

On a different note, another factor to take into account when evaluating commuting times is the possibility of changing jobs. When I bought my house, I specifically looked for a short commute time, but not just to my then-current workplace. I also took into account commute times to other places I might end up working if I changed jobs (other campuses of companies in the area which employ large numbers of people in my field, especially places which employ friends of mine who could refer my for positions). By over-optimizing for my then-current job, I felt I would have increased my risk exposure if I lost my job or became unhappy with it, as well as reducing my ability to take advantage of new opportunities if another employer could make more productive use of me and cut me in on the additional value created.

One mistake I did make in buying a house was very badly underestimating the cost in time, effort, and cash to make repairs and improvements to a house purchased in poor condition. In hindsight, I think I made the right tradeoffs, in that after spending the money I wound up with a house that will suit my needs better and for a longer period of time than I could have afforded by paying the additional cost to buy a house that was already in good condition (this includes the substantial benefit of being able to customize aspects of the house to my desires as I made repairs and improvements), but this was a happy accident despite the major misevaluations I made when planning the purchase.