Elrihor, I'll give you my thoughts on why the AH prices are rising:
What I'm sure you're most undoubtdly (I can't spell) noticing is that more and more players are starting to join our fun loving game. Now, when I started in may I remember there being about 2-3 thousand people on during primeime, check it now, well over 3 grand during NA primetime -- and I've seen it well over 4 and even 5 grand during JP primetime.
This large mass of players is now starting to approach the higher (the bulk of them being PS2 users). As more and more players start up, and more and more players get into the mid to high level range, the demand for the best equipment goes up. Now, what has yet to change in all of this? The drop rate.
Sure, there are more Kotes, hairpins, etc in the market, but the majority of these items are useful even to level 75 players, so they never get resold. The rest of the players are left to fight for the 7-12 hairpins per day, the maybe half dozen sniper rings per day, the 8-10 signas per day.
When lots of demand is place on these items, simple economics tells us that the price is going to go up, because the supply has not changed.
Now, I will agree the the gil farmers might play some factor into all of this (note the word some), however you cannot blame them when you are not motivated enough to go out and get the the claim and earn the drop.
An item is worth what someone is willing to pay.