I made almost all my money in game from BS'ing. That being said, I had a reputation on server for being the go-to guy when it came to BS'ing since I had all but a few sunwell recipes. So that clearly helped my earning potential. But even without rare recipes I used to be able to make some money crafting the starting pve and pvp gear -- materials are usually very cheap. Once you add a few high demand rare recipes to your list you can start making a very pretty penny.
i dont know whats it like on the servers you ppl that make gold with bs play on... but on mine, high pop EU pvp, everything BS is dirt cheap because of competition. blue sets costs like 10-50 gold more than the mats, epic crafts are dozens at the AH, and EVERYTHING gets undercut the next half minute.
its a great prof (paired with mining) to have at expansion start, and thats about it as far as money making goes on high pop servers.