If you keep your eyes on the trade channel you can find some realy good deals. One of my favorite that a lot of people do not pick up on are the people giving away good enchants. It is very common for people power leveling encahnting to just give enchants away. Any enchant those people can not give away gets burned up over and over on some item in their bag.
Sometimes they offer a good encahnt for free. If you are quick to spot this you can grab several scrolls for them to enchant. I can usualy get 5 at a time when I spot this deal. Then sell them in the next few days for 60-90G each.
A lot of people still don't know how to enchant a scroll or that it still gives a skill up. Even if you have to buy the blank off of the AH it is still easy gold when you spot it. I bet I made 1.5k gold off this in the last year.