Simulators & Cheap Deals
Many CCNA candidates do not have access to routers to practice the various CLI (command line interface) commands that are critical to remember and understand in order to pass the exam. Here are some places to go to find a simulator that provides a CLI environment in which you can practice basic router configuration. Some have downloadable demos.
SemSim provides training for Cisco certification exams through exam and router simulation Their site also includes free learning center for cisco exams CCNA, CCDA, CCNP!
Sybex has put together an excellent simulator called CCNA Virtual Lab - Platinum Edition by Todd Lammle for the 640-801 exam.
You can download a workable demo of Router U's simulator called Krang.
R1R2 Labs provides free (for now) on-line access to actual routers for practice. The catch is that the routers have to be available (lots of folks seem to be using them).
Simulated Networks provides usable, downloadable demos.
If you want to buy your own Cisco Networking Equipment at a great price, then visit the folks at UsedRouter.com!