Alchemy tips?

For some reason it's cheaper to buy elixirs and potions at the AH rather than crafting those yourself even considering the 20% bonus from masteries.

I'm guessing mats and consumes prices are fluctuating over the week and I'm wondering when is usually the best time to buy mats and when is the best time to sell consumes?

Like I would guess there's way more activity over the weekend, but does this translate into more people farming mats though leading to more offer and lower prices, or more people online needing those mats thus translating into higher prices?

Also, is there any addon to track this? Auctionator price history thing is a bit limited...