My 2 cents.
You can build better for less. If you have the skills, tools and time.
I'm 0 for 3 in that department. So I bought a system for a little over $2000. It was a cocktail table (my choice since I had a bit of room behing the sectional, but no wall space-stand up units are easier to find). It can be played vertically or horizontally (controls on 3 sides).
Games include PacMan, Ms PacMan, Donkey Kong, DK Jr, Space Invaders, Galaga, Galaxian, Zaxxon, 1942, 1943, Time Pilot, Gyruss, Frogger, Millipede (ugghhh...no trackball though...ggggrrr....) on the verticle side. It has Joust, Robotron, Moon Patrol, Mario Brothers, Stargate, Defender on the Horizontal side.
It will be upgradable when new boards are released.
These are Jamma Boards-not MAME. So, no computer to boot up. They play like the real game...turn it on, select your game, and play.
If you want MAME, there are a ton of options. If you want Jamma, there are a ton of options.
The biggest problem I see with this system is that these are all 2nd and 3rd tier games. I saw no point in getting this if Ms PacMan, DK, and Galaga weren't on it.
If you want to make it yourself, a 60-in-1 board can be had for under $250. Just need to be able to hook it together with other stuff...