I've got a toon with every glyph. Initially took the profession for the shoulder enchant, actually; but eventually got all the glyphs.
I've also got about 7-8 people who actively watch the glyph market on my server, and constantly undercut you on glyphs. Most glyphs are under 5g to buy.

Conversely, there are three of us who list a lot of cut gems daily.
One of them has agreed to match my prices, so we basically add each other to APM.
The other guy insists on undercutting us, but is not on that often and happens to be a friend for all of my toons; if he's been on, and was in a city, I relist gems.

I guess it depends on your market. I've heard glyphs can be lucrative.
The herbs sell better than the glyphs, at least on my server.