loveroots,
Read the Odom blog at Networkworld as posted by lerdalt, Wedell Odom did a good job on both a CCNA lab and a CCNP lab.
You also might keep your eye out for a 2520,2521, 2522 or 2523 for a Frame Relay switch or get a NM-4A/S or NM-8A/S for the 2600 or 3600 and use one of them as your Frame Relay.
Keep your eyes peeled for WIC-1Ts - these work great with either the 2500's or the 2 Network Modules listed and back-to-back DTE/DCE cables for your serial connections between the routers.
You will also find a nice sweet spot on 2610XM or 2620XM routers on Ebay now I have seen them go for $75 to $110 - they have 1 Fast Ethernet, 2 WIC slots and 1 Network Module slot and can run 12.4 IOS's. 3640's are also nice but make sure you factor in the cost of Ethernet/WIC Network Modules or Fast Ethernet/WIC Network Modules. But the 3640's will also run 12.4 and just about any Network Module or WIC so they make great lab routers.
Good luck and read back a few pages of posts here to see what has been discussed on labs!
E.A. Broda
CCNA, CCDA, CCAI, Network +