One way of doing it using three routers:
Get three 1601 R routers off of eBay with power supplies and make sure you get at least one console cable out of the deal. They are selling the routers these days mostly without the power supply, and f*ck me if I know why. If you give yourself a few days, you should be able to find three with power supplies. Only buy from sellers who know what IOS is on the router and make sure they don't blow it away like Cisco tells them to. You really only need one IOS -- you can copy from one to the other two with no problem using the TFTP software on the Cisco Web site. Try to get them with a minimum of 8MB flash memory cards.
Get a WIC-1T card to fit into one of the 1601's. I got one recently for $25 plus shipping.
Get two V.35 serial to male cables and two V.35 serial to female cables. This will allow you to simulate connections to DTE equipment and connect all three routers. They're very expensive cables but you can get them really cheap on eBay.
Make sure the computer you are using has a serial port. If not, get a USB to serial conversion cable.
That's all the equipment you need. A book like Lammle's will tell you how to connect them all and get them up and running.