I can't ever remember running out of money to train with (although with all of my alts, I usually send about a hundred gold back just to keep repairs and item purchases rolling), but I don't know that I've always had money for a mount at 40. I have a priest right now who's 45 and still running around, just because I've never actually focused on making money long enough to raise the cash. Then again, on my disenchanting rogue, I've always had tons of money to go around, and even sent some up the chain to my main.
Is there a problem with funds at low levels? Do you find you have too little cash from 20-60, just the right amount, or even too much? I think the money flows pretty freely throughout the game at this point-- there are enough ways to earn money at almost any level that if you put in extra time, you should have all you need. But how's the tuning if you don't put in the time? For a character just leveling up, does the game give out enough cash to do it all?