I was outfitting a new set of armor with runes and insignia, when I noticed the prices of some of the runes had risen significantly. For example, I recall a time when minor vigor runes were practically worthless. I'd sell them to the rune trader by the handful for 25g each just to clear some inventory space. Now, the rune trader sells them for nearly 2k!
(Warning: Economic analysis follows. If you are easily bored, better skip the next two paragraphs)

What caused this dramatic price increase? Well, it either has to be a decrease in the supply or drop rate of the rune, or an increase in the demand for it. While I have not personally noticed that these runes drop less frequently than before, it is possible, since the addition of newer runes to the game may have lessened the availability of other runes. However, there weren't that many new runes, and assuming the relative distribution among runes to be the same, at most there should only be a slight increase in price, nowhere near the 20x rise.
That leaves an increased demand. Not just an increase, but an incredibly massive increase. The best explanation I can think of is that people have been using these runes to equip their new Heroes. Consider that each player may have as many as 8 characters (considering all 3 campaigns) and possibly more, through the purchase of slots and preorder bonuses. Now, figure that each character that enters the nightfall campaign gains the ability to have heroes, and rather than sharing heroes across an account, each character has duplicates of the same heroes. You could easily have 20, 30, or more heroes associated with a single account. That's a lot of heroes needing a lot of equipment, particularly runes. Superior Vigor Runes are way too pricy to supply on that kind of scale. Even Major Vigors are a little on the high end too buy more than a few, so people make do with the Minor Vigors. But that causes a dramatic rise in demand, and skyrockets the price up to near the major vigor runes (which last I checked were at aobut 3.4k, less than twice the minors, and not much higher than the pre-nightfall price).
Well, I hope I haven't lost too many people with this economics lesson, but to cut to the bottom line, the addition of heroes to the game has had a huge impact on the cost of what used to be the low-end, inexpensive items. What's the solution? Personally, I think hero armor upgrades and weapons should be more dependent on the PvP equipment system. Heroes already have access to any skills unlocked on an account, why not treat their equipment the same way? It makes sense, especially when you consider having to equip the same hero several times over (once for each character who uses that hero), and in light of the economic drain heroes are causing to the game economy. Or is that Anet's purpose, to make another gold sink? If so, it's only partially effective, because players still receive money for the runes sold to the trader, if not quite as much as gets put into the trader.
What do you think? Does the rise in low end rune price have anything to do with the heroes, or am I way off? Is this a valid solution, or does anyone have better ideas?