I suppose you could do it, but I would also think that having access to either some equipment and/or on line labs would greatly benefit you.
Most of the "CCNP" labs you see on Ebay and the like are usually a couple of routers and a switch. As always, the more stuff you can play with and hook together and wreck and rebuild, the better.
In my pile o' stuff, I have a 2502 router(two serial & 1 token ring),
a 1601( 1 ethrnet, 1 serial and one WIC-1T 56k serial card),
and 2 1004 ISDN routers, (but I can only use the ethernet ports, because an ISDN simulator to utilize the ISDN ports is CHA CHING! like 1800 bucks is the cheapest I have seen one.

)
I also have a Catalyst 2924XL-EN 24 port 10/100 switch as well as 2 cisco 1502 micro-hubs, and the latest addition to the mix is a Synoptics token-ring MAU and 2 T/R nics.
I would guess that you would need at least 2 routers and a switch to do most of the stuff that is covered on the CCNP exams.
You also might try searching for on-line lab sites, there are several on the web where you can rent time on remote lab equipment for a fee.
I bought all my stuff here:
www.systemresale.com
I got all the stuff above except for the token ring stuff for about 2500 dollars (U.S) shipped to my door. They have pretty good prices, the switch I got was going for at least $1300 and up on the web, and I got it new in the box for $975. It has the enterprise edition software on it, so it has a CLI to set up VLANS, etc, and can do more than the standard software that comes with a standard edition switch.
Their inventory changes from day to day, and the website may not reflect what they actually have in stock, so you might want to give them a call to see what they have on hand. They will even buy the equipment back from you when you are done. Hope this helps a bit.
