I'm beginning to study for the switch exam and was wondering if someone could recommend some cheap hardward. I currently have a 3750G at home, but was wondering if I could get away with using that and maybe some 3550s or 2950s.
Cisco 3550s with the EMI image are probably the best way to go and you could use one of these with your 3750 to test out most of the objectives. You may also want to consider a couple of routers (either physical or emulated) to test out VRRP and GLBP as these features aren't supported on the 3550.
I'm not sure whether the 2950s would add any value as there are various features not available on these switches and several of the commands are also slightly different.