If you have no skill whatsoever and you want a mame cab, you can mod this. Shortly the new images of retropie for the new Raspberry Pi model will be available. I think I already saw kits to do the conversion, and there's plenty of videos on youtube.
I don't know about installing a CRT, but I'm interested to see if the RGB-PI works on the new model straight out of the box.
For a bit more $ and no Raspberry PI you can also stick an old tower in and install lakka.
I hear they have some 240p support in the works too.
Since I'm making repro cabs from scratch with blueprints and customizing them to whichever CRT I'm building around it (super cheap), these don't interest me, but watching the videos I think anyone investing to upgrade without too much mess, space, woodworking tools, or skill will enjoy only a mild challenge.