Getting Hands-On in Cisco IOS is getting cheaper, now we have Dynamips, Dynagen, PEMU and GNS3 all Freeware utilities that uses real IOS to emulate Routers in our Computer.
You can create real world scenarios using those softwares, it´s REALLY COOL! I´m using it in my studies with IEWB Vol. 1 and it´s working great so far!
Of course, you´ll need a good machine, LOT´s of RAM, but, it still cheaper than renting a rack for doing just small labs.
For full scale labs I suggest you to either use 2 PC´s or renting a Rack.
Dynamips (Cisco Router Emulator):
Dynagen (Front End to be used with Dynamips - It includes Dynamips in it´s package):
GNS3 (Graphical Network Simulator - It works with Dynamips, Dynagem and PEMU):
Off course, those softwares does not include IOS and Cisco Software, you need to get it on your own!