On my realm, there are about four major posters, so not much competition. Prices bounce around between 30g and 350g for any given glyph. We reset the price high if none of that glyph are available and then slowly undercut by a couple copper with one or two glyphs until the price bottoms out. It's a nice ebb and flow.
Well, a new poster came on the scene and was doing the same process, but undercutting every hour and this really got under the skin of one of my competitors. He wasn't selling any more than two glyphs a day, so, he made a "firm wall." This strategy involves posting a large number of an item at a low price, a strategy useful when you want to prevent someone from buying you out and resetting your goods (Notice that this wasn't what was happening?)
This is frustrating for the rest of us though because this wall was set at 49g and encompassed all craftable glyphs. In short, he crashed the glyph market.
Total Daily Value of my Posted Glyphs
Which brings me to my advice for new goldmakers and one of my cornerstones that I'm constantly harping on: diversify. When the new poster entered the market, I made less money in the glyph market as well, but it didn't phase me, because I'm involved in other markets. There will always be a market that is down: Blacksmithing will have underpriced ore and will be selling too cheaply, glyphs will have awkward competition, transmute will just...not be profitable because screw transmute, that's why. Diversification prevents the emotional involvement and thus the emotional over-reaction to competition that occurred here.
There has never been a time when every market is down at the same time though. Use a few different professions. Use TSM so you know what is profitable. Run raids so you aren't always relying on professions. Level some pets. Farm ore, so you're always profitable. Sell some green MoP items.
And that's it. If you want more updates, or more information, follow me on Twitter, YouTube, or Facebook, and until next time, remember that the secret to goldmaking in the end is just to
Search. Craft. Post.