Thanks for the GREAT advice so far, everyone. I suppose a bit of clarity is in order.
As mentioned, this is my first time doing anything like this. I have been wanting to do it for a long time, but you know...taking that first step is the biggest.
I wanted to get an NES Classic just to relive the days of my youth...but since those are a high-value item...
And then I realized I spent just as much time in the arcades...and I like arcade games more anyway...it was time to look into a MAME machine for not much more than what the NES Classics were going for on eBay. Did some searching around...and yup...I saw the Vigolix plan and thought it would be a quick and easy way to get started.
After doing some research to confirm my direction, I ordered up a Raspberry PI, a joystick controller, some joysticks and buttons. Then I went and bought a .50 thick piece of 2' x 4' MDF. And then I stood next to it and realized that it would be TINY. I was reading that people were scaling the dimensions up in size to make it bigger, so I did...and then I started tweaking my design and now it looks nothing like the original plan. Isn't that how it works?

I got the cabinet sides done and got to a point where I needed to define the monitor size to determine the width of the cabinet, which is where I posted here.
Thanks to the advice above, two days ago I ordered a Dell UltraSharp 2007FP for around $40. I figure it will do nicely. I'll keep everyone posted.
BTW...where is the best place to post a build log?
Thanks, all!