AH control on a smaller scale is a pretty simple option. Glyphs are one way I go. There is a very large range in glyph prices. You can find some priced between 10 and 100 gold at the same time. It's very easy to flip and undercut, while making a nice profit. Timing is also important. Post during pre-raid times.

The Glyphs are just an example. There are many more you can find out there on the AH. Just have to do your research, or find an addon that does it for you.