You just answered it in part. Having to re-pack a headset is something you shouldn't have to do anymore. More than that, the difference between a loose bearing headset and a higher end sealed cart headset is noticeable IMMEDIATELY. Add a bunch to that if you ever ride in dust/dirt/rain/salt/etc, as everyone does. The headset is not a component to be skimped on whatsoever; it plays a pretty important role in how your bike handles (and for the record, does go through quite a bit of stress).
It's the difference between night and day, and that's before we begin discussing durability.
Using a nicer sealed bearing headset vs a $10 set is like throwing a frisbee vs a dodgeball. That's a weird analogy, but it really illustrates the difference nicely.

JellyMeetsJam, i ride shimano 600 on my nishiki conversion (rain bike) and dura ace on my bob jackson. Both are sub $100 (the 600 is significantly lower), and both are terriffic; +1 on bitboss' ultegra recommendation. I'd seriously consider avoiding a loose bearing headset if at all possible, as repacking a headset every month or so can be a real pain (and not repacking it can be even worse). A well installed quality headset can be pretty much ignored and adds a ton to a pleasant riding experience.