One potential option for you (IIRC, you are in the GTA, right ?) is that there are a bunch of what look like "conversion" cocktail boxes (
box being the operative word) floating around Southern Ontario that can be had fairly cheap and are easily converted for emulation (since they seem to have been designed for exactly that purpose).
I picked one of these up in March (fully-functional Perfect Billiards bought on eBay for C$160 with pickup in St. Catherines) to build a three-sider for the cottage for my kids and sisters-in-law. While they had no interest in trackball or spinner games, the sheer size of the control panels on these things would allow for a multitude of controls (compared to a normal-sized cocktail panel).
I don't seem to have pictures of what mine looked like originally (with hideous pale gray laminate and generic overlays), but here is a pic of one (neither complete nor working) that was at the April Starburst auction:
http://www.kingscollege.net/cooke/NewestMachines.htmThe CPs come off and can be mounted horizontally as well (that was the way mine was originally configured). All I did was prep, paint, drop an ArcadeVGA into a machine, build an extra-long panel for the horizontal and run the controls through an iPac2. Below are some pics of my Plain-Black-MAME-Box in a not-quite-finished condition (still had to finish up the horizontal panel).
It ain't all that pretty, but it sure was a cheap and easy build and is great for the cottage (e.g. if someone steals it, I won't be heartbroken).
Having said all of that, of course, it may be tight trying to get a 21" monitor into one of these ...
Cheers.
[EDIT: I actually played this machine for an extended period this past weekend and am contemplating adding a fourth panel ... I had a Tron craving and trying to play with regular stick and buttons was just wrong. At the same time, I may add a spinner to one of the vertical panels.]