There are a few things I want to mention about gold and trades in general.
First of all, the server doesn't sell any gold, but you can buy gold with coins from OTHER PLAYERS.
If you are willing to give gold for coins or coins for gold, that's UP TO YOU.
Of course, you need to have at least one donated account to do that, but it is merely 10 coins, which means approximately 20k gold on Icecrown at this moment.
Every single item in the game that can be sold has it's price in gold.
That price is decided by players, not by the server.
It is a free market, everyone can sell or buy for whatever price they want.
If you don't want to buy a pet for 5k gold, just don't, if you don't want to pay 10k gold for one single item, nobody will force you to.
It is YOU that decide what is worth buying and what isn't.
Everyone has to decide for themselves if they want to pay a specific amount of gold or coins for an item.
Let me give you some examples:
I would never pay 5k gold or more for one item, even if it is was almost bis, this includes any boe like profession pants or choker.
I wouldn't pay 23 coins or about 50k gold for 1 BiS item, not even the rs25h trinkets, because I can get them by actually killing the bosses.
I am willing to sell 25k gold for about 10 coins and then buy a mount that is unobtainable in the game for 30 coins, which means about 75k gold.
I am willing to sell 40k gold for about 15 coins and then buy a pet from website because, guess what?, you CAN'T GET IT ANY OTHER WAY.
I am willing to pay 100-200 gold for 1 flask because I have herbalism and alchemy myself and I know the effort and time that takes to make them.
All of these examples and EVERY OTHER PRICE in the game or outside the game is decided by the economy itself.
If 98 people out of 100 are willing to pay 5k gold or 23 coins for 1 item, the other 2 guys can't complain and get it cheaper or for free.
If you are willing to work and put in the EFFORT and TIME to get the gold, the items, the achievements or whatever else you want, you WILL GET IT.
The value of gold is influenced a LOT by the TOTAL AMOUNT of gold that exists in the game at any given time.
That means if most players on the server have 10k gold or more in total, they are most probably willing to pay 5k gold for some item.
If you are poor and barely have 1k gold on all your characters then you should not buy an item for 5k gold and focus on more important or efficient stuff.
If ALL THE GOLD in the game gets halved, then on average, following the above example, everyone will have 5k gold or less, depending on what they did.
That means that MOST of these people will not be willing to pay the same amount of gold for the same item.
There will still be lots of items that will sell for the same amount of gold because EVERYONE IS WILLING to pay that amount for them.
Gold gets into the game, it gets created out of nothing, just by drops and quest rewards.
There are 2 possible situations, one with squish, one without.
With squish: some of the gold is sinked out of the game, prices vary a bit, but over the years stay the same and don't fluctuate by a lot, usually up to 100%, most of the times less. New people can afford most things and can buy everything if they are willing to put in the effort.
Without squish: more and more gold exists in the game to the point where having 100k gold is meaningless, prices go higher and higher, exponentially and proportionally to the time that passes. New people have no way of catching older players from behind and it is very hard or impossible for them to become part of the economy and can't buy anything they need/want.
If it was up to me, I would do the squish more often and UNANNOUNCED, so people CAN'T PREPARE FOR IT. That would make people actually use their gold and put it in circulation, rather than keep it safe and away from the economy. But I bet everyone would get pissed if the server would do that, even if it would actually be the MOST "HEALTHY" for the economy.
So you should be GRATEFUL that they tell you every year instead of just doing the best/right thing.