I didn't keep a perfectly exact count, but I believe it took ~40 potions to increase my Alchemy skill from 24 to 25. Now, I could activate the Thief Stone to help, and I will. But even with that, this takes about 4x longer than in Morrowind or Oblivion, and the ingredients are more expensive and/or much more difficult to gather in large numbers.
Am I missing something, or does Alchemy pretty much have to be increased by buying training now unless you have a huge chunk of gold to buy thousands of ingredients with?