$11.99 is the MSRP price. What each store decides to charge is solely up to them. Some sell for a little less, and some for a litle more. Most times, most people look at these Micro T parts as being reasonably priced or cheap. This is in compairason to most other R/C parts.
Killers useually has good pricing and decent stock
http://www.killerhobbies.com/items/t...528-detail.htm
......and as you have found out, these are for the hubs only.
If you take a look at this other pix of a complete diff
http://www.killerhobbies.com/items/t...515-detail.htm
there are bearings on there already