It depends on a lot of things, but I was also doing my CCVP too, so if I were to buy routers, it would only be ones that have voice functionality with DSPs etc. Personally, I think there's so much you can do with GNS3/DynaMIPS that if you structure your study properly, you can minimize the time you need for racks etc.
When it comes to the layer 3 routing protocols, multicast, access lists etc....DynaMIPS is absolutely flawless. So, what I did is I said that I would focus my learning on layer 3 routing protocols first. For Bridging/Switching, I am currently using the 3640 etherswitch module supported by DynaMIPS. You can learn qutie a bit of switching theory using that, considering the essence of SpanningTree/LAN Switching hasn't changed with the advent of the 3550s/3560s.....only features/functionality has improved but I'm at the point where I'm learning the fundamentals of LAN Switching theory, not the intricate aspects of the 3550/3560's special features.
DynaMIPS:
I have come up with a hybrid strategy, but it depends on where you're at with your studies and your methods b/c I'm reading Routing TCP/IP along with doing Vol I labs of the routing protocols.
I have been using GNS3/DynaMIPS primarily for all of my learning so far. DynaMIPS also supports a 3640 switch module so you can learn the essence of spanning-tree with it, but you will be out of luck trying to do advanced 3560/3550 stuff.
So far, I am using DYnaMIPS to cover all of my Frame Relay, layer 3 routing stuff since it's virtually identical to a real lab. Aside from layer 2 switching + QoS (which has some verification issues I hear), DynaMIPS does the job flawlessly.
Rack Rentals:
I plan to utilize rack rentals when I need to do my bridging/switching workbook Vol I and I need to know 3550/3560 specific functionality. I am trying to get through the relevant parts of Cisco LAN Switching by Kennedy Clark and learning that is pretty much router independent. I can do that using GNS3's support for the 3640 16/32 port switchport module IE uses for their Vol II workbook.
I really only contemplated buying equipment for the sake of switches, but if you buy switches you'll also need routers too, so I have decided to use racktime whenever I'm doing full-fledged labs that require 3550s/3560s.