As ohmikeghod said, the lowest (and a good first wand) can be attained by an Enchanter, anyone who has taken the Enchanting profession - you can do this yourself if you want although its a pretty big money hog.
As for your other Wanding options, some wands can be attained for free through quests - although its hard to specify for you since I don't know what Race you are.
Your best bet past that is to check the Auction houses, as most wands drop as regular Greens that are Bind on Equip and can be auctioned.
For the most part, the best Wands you can get are going to be drops from Instances that require groups to run. If you're on the Alliance side, and can get near Westfall a great bet is
Cookie's Stirring Wand, while if you're in the Barrens you're option is harder to attain, but called the
Firebelcher.
While these are relatively annoying to attain, if you like to group regularly they are worth the effort, as Wanding is a powerful way to add a good amount of damage without costing mana - Stack on some DoTs and start wanding.
If you do not plan on doing these group instances, your best bet until the 20s is still going to be a
Greater Magic Wand which is also made by an enchanter. Either make some friends, or go run to your Auction house and look for wands.