Levelling a profession without the gold to purchase the required materials is a drag. Then again, the grinding is even more of a drag. If the levels were filled equally, there would be enough lower level gatherers and looters to keep the AH stacked with the materials over the level and profession skill levels.
However, this is not the case, at least not in the first generation servers like Thunderhorn-EU. The level range of the toons is very, very top heavy, and the levelling through 20-60 content is ultra fast, even though the 40-50 levels of death are still revered as such. I've noticed, however, that the current speeding up of levelling has in fact taken that hellish grind stage off, and the level range 40-50 has become 50-58, only to speed up at the entry to Outlands.
The result in the materials available is clearly seen in AH: Mageweave is almost non-existing, Runecloth is pretty scarce. Both being the 40-55 range stuff. I also heard the same from my brother who's toon is Leatherworker: certain leathertypes are missing from AH or are extremely overpriced, mostly due to the fact that they are scarce.
Sadly, this leads to the fact that if a new player comes into the game, s/he will face the burdens of outlevelling the content and at the same time outlevelling the 'natural' ways to get the materials needed for the professions. Double burden.
And it's of no use to start training the professions when the toon is capped, if there is no supply of the materials in the market. Add grind to the grind for the raid buffs, repairs and getting the gear to be able to enter the raids...
Ouch. Not a pretty picture.