Not everyone has lot of level-capped alts, so I want to share this advice to those of you that have just one or two level 80 characters. You'll probably have some really low-level character that could make a profit out of Inscription!
As it is now, Inscription becomes valuable at skill level 75, when you start making "Minor Inscription Research" that let you learn new Glyphs. Since the Glyph you (as for everyone else) learn is random, you could end up with some very valuable Glyphs known. So you just need a level 5 character to start to gain thousands of golds from this profession.
You can do this also if you already have a scribe and you want to double the number of minor research you can do... But you should be aware that this will be good just on the short time (sooner or later you'll discover everything anyway) and can make management quite tricky. Try it at your own risk!
Obviously, it's better if you don't use the character with which you play the AH game... It could fill your bags even more and make things messy. Do it just if you're sure you can handle it.