I've got the Dremel 3000 with the flexible shaft. $128 from the green shed.
I also got the plunge router attachment. Some on the forum say that the StewMac plunge router attachment for rotary tool is much more stable (
http://www.stewmac.com/Luthier_Tools...uter_Base.html).
I can't comment as I've only used the dremel one, but it does look a lot more solid being all metal.