Possible solutions: nerf dungeon experience unless there are five people in the group. Drastically nerf experience if there's a high level character along. More importantly, fix the pacing of outdoor content so that people won't get frustrated and turn to cheesy methods like this -- even hardcore, Mythic-raiding, altaholic Day-1 Warcraft players like myself.
If the new Battle.net balance has given rich players a new incentive to liquidate, and the spiking prices are a result of them trying to sell all their gold at once? Prices for tokens could settle much lower once that stash of gold has been depleted. This seems likely, because there’s a compelling new reason to sell gold, but no new reason to buy it. Blizzard has a good way to drain those gold reserves from the market.
Another dungeon farm, this time in Uldum, Tol'Vir trash mobs drop loads of embersilk cloth. Stacks of this tend to sell for a tidy profit, though prices vary depending on the realm. A typical clear of the dungeon takes about 5 minutes, netting about 7.5k per hour in cloth, vendor trash, and various other drops like mats and BoEs. Pick up a Potion of Treasure Finding and farm to your heart's content! It's just as profitable on normal mode as heroic, too, making farming all the quicker and easier.
Make sure you have the two Flight-Path toys purchased, as this can save you time. It won't have EVERY flight path, but will have major locations for faster travel if you need to switch zones entirely(which you will). If you buy the toys on one faction, it unlocks for the other faction as well. So don't spend double the gold! These toys can be found at the heirloom vendor(Undercity for Horde, Ironforge for Alliance)