If your going to be using it primarily for a MAME machine, CGA is all you need. If you plan on using some windows apps or playing pc based games, you may wan't to go the hybrid route although that will up the price quite a bit. I do have to use windows on occasion and have the desktop set to 640x288 which is clear, but icons and text are very big.
Arcadeshop is very reasonble, 179.00 for the monitor and shipping was like 16-17 bucks ( I'm in FL, so I was pretty close, your mileage may vary the amount ), but still under 200.00 I would think, as with Happs, it's a guessing game till after you order.
I did use a Vga hacked cable, I purchased a ArcadeVga and hacked cable from Ultimarc at the
same time and was floored by the quality of the games.
Tim