There are a few ways to set this up, and yes a lot of it comes down to preferences.
Some of the differences I think you are over looking though would be:

1 comp, 5 accounts, 1 monitor: You have one large wow, and 4 small. This makes it difficult to see and interact directly on the slave accounts, however with Keyclone and a few of the other apps out there, they have excellent PIP swapping capabilities to allow you to instantaneously bring any of the slave computers to the lead. This does how ever require a bit more hardware to run efficiently.

5 comps, 5 accounts, 5 monitors: This will be the least resource intensive set up er machine, with the network KM software out there it would act as though you have 5 monitors on one machine and can be very smooth. One thing you have to be careful with is your field of view, if you get monitors that are too big it becomes hard to notice your slave accounts quickly. Also, unlike 1 comp, you can not swap slave accounts to your central location. Many people here are running a large wide screen for the primary and smaller standard screens for the slaves to help keep them all in their field of view.

3 comps, 5 accounts, 3 monitors: This is how I run mine, more so because I am using the equipment I have. 3 wide screen 24" monitors, the two "wing" monitors are turned vertically and two accounts are split equally on them. This set up has the same fall backs as 5 comps, not being able to swap wow locations on the fly. But it also keeps your accounts close together and requires a mid range amount of hardware.

There are of course many other combination that can be done, but I believe most would fall under one of those three categories.
The other thing to consider with the "no time or budget factor" is where the actually bottle necks in computer gaming are.

CPU = This bottle neck is mostly non-existent now, most processors you can find will handle wow without an issue
Video Card = For wow, this is also not so crucial anymore, find a card sitting right at the price break, Usually around $150
Memory = It's Cheap, get what you can. If your running a 32 bit OS, 3 gig's is your limit, if your on 64, 8 gig's should be overkill
Hard Drive = This is the most over looked and currently the biggest bottle neck today. There are some great articles written here about running Symlinked and solid state drives. If you can afford them, get them.
Network = This is one a lot of people over look, and really is only relevant on multiple machines. Make sure you get a gig switch and nic's, this will make your internal network traffic much smoother and reduce the lag and headaches while passing keystrokes and mouse movements.