The Dos Equis commercial comparison is awesome.

Although there has been a whole lot of good reasons for using a straight, I wanted to add a couple comments on the advantages. The number one advantage (for me) is that once you learn to shave with a straight, it will almost certainly increase your shaving proficiency with any shaving tool. You'll understand more about how to cut the hair and most importantly, you'll know more about your own face (shape, angles to cut, bad spots, etc.). You could buy a sub $50 shave ready razor off of classifieds or whippeddog and it would be worth it just for the learning experience.

If you want a good shave that is as quick and as cheap as possible, I would suggest DE's. You can get a good shave, it's relatively fast, and the long term price is quite low. In theory, a straight could be cheaper long term, but how many people buy only one straight? If you want to get as close a shave as you desire (at the time your shaving) and you want to enjoy the shaving experience as much as possible, go with a straight.