To enchant or not to enchant

with each alt I level, I make it a point to wear the best gear I can reasonably get my hands on. I'll shop the AH to replace out-of-date gear (if I can find things at reasonable prices), I'll research what I can get from quest rewards and dungeons in my level range and I'll often throw on some cheap enchants and/or gems to make my gear that much better.

this practice of keeping my gear above average is pretty easy and cheap to maintain until I hit northrend. at that point, the leveling pace slows down a bit (meaning you're holding onto gear longer) and the difficulty of dungeons relative to gear and skill levels goes up a (small) notch. there's also some really great gear available from some early quest lines and dungeons that will last for several levels.

this raises the question, then, of how much is worth spending on enchants/gems for level 70-79 gear? enchanting expenses are pretty low in the sub-70 levels as the cheaper enchants are just that: cheap. those enchants don't stretch as far in northrend, however, and the mid-range and high-end enchants and gems can get pricey fast.

is it worth it? on the one hand, slapping a mid/high-end enchant or gem onto an already good piece of gear turns it into a great piece of gear. it has a direct and noticeable impact on your performance and you'll hang onto it for a few levels. on the other hand, you know that once you hit 80 and start running heroics and toc/icc 5-mans you'll be replacing all that gear pretty quickly with new drops and emblem gear (which you'll then have to gem and enchant...).

if you're playing a dps class, it's simply a matter of whether you have the gold to burn or not. your dungeon group is not going to wipe just because you didn't enchant your gear and are doing a few percent less dps. it's not quite so simple if you're playing a tank or healer, however, as the survival of the group rides a lot more on your individual performance. for example, as a tank you have to balance the cost of buying a few stam enchants with the benefit of having a larger health pool for when pulls go bad or the healer is weak. the same holds true as a healer... is it worth buying a few int/sp gems so you can throw out more/bigger heals when a tank is squishy or doesn't hold agro well?

decisions, decisions...