The vga driver board was ordered off ebay from a china supplier, I ordered the one with the remote which came in at about £25, when you order you leave in the order comments the type of screen you have and the supplier gives you the correct cable. It’s pretty much plug and play. I have two different types, the cheaper version at £19 has no remote but is plug and play it just works, the dearer one however had to have a firmware update in order for the ipad screen to work with it. What wasn’t included was a 12v transformer, so you will need to pick one of those up.
I have two icades, one running retropie using a raspberry pi2 and another running a NVidia shield portable, left the console out one day and my dogs had chewed it up a fair bit, so I modified it with a quick release plug so it could still be used as a portable but currently sits permanently in the back of the icade running hyperspin.
I do prefer the setup of retropie better, much cleaner interface.
to save effort buy the more expensive vga driverboard as they have the remote and a built in amplifier for external speakers, plus an external 5v USB this will power your pi. With a 12v 2amp transformer you can run everything purely from that, no need for separate cables for speakers and hard drives etc.