Fortunately, I've learned a lot from the one I have.
Late 70s Midgets are cheap and plentiful. Most people don't like them as much because they are laden down with smog controls, a single barrel carburetor, and are heavier than the older ones. Some folks think the rubber bumpers are ugly, too.
The 1500 engine used from 75-79 is the same as the one in the Triumph Spitfire. Parts aren't too hard to find. Moss Motors and Victoria British are your friends for finding parts.
The factory electronic ignition used in those years is doomed to fail, they were notoriously unreliable. Pertronix makes a nice replacement. A tip, since I had to install one, the resistor attached to the pedal box is NOT the ballast resistor, it's part of the original system. The ballast resistor is actually resistance wire built into the wiring harness, not a discrete resistor. Just keep the existing wiring if you go the Pertronix route. Don't leave Pertronix ignitions on with the engine stopped for more than a few minutes, they tend to fail.
The 1500 Midgets aren't particularly fast. They are up to 4000 RPM in 4th gear at 70 MPH, and it's screaming at that point. The 1500 engine has notoriously weak crank bearings and rod bearings, so running in that region isn't kind to them. There is a 5-speed conversion available, but it's expensive and not trivial to install.
Thrust bearings are a weak point. If you ride the clutch a lot, the rear thrust bearing takes the force of the springs, and it wears the bronze plating off. Then it starts wearing rapidly, to the point wear the crank travels far enough to allow it to slip out. Check the crankshaft endfloat, it's the best indicator of the health the the thrust bearing. There's actually a guy who designed a better thrust bearing for the TR6 engine, which uses exactly the same thrust bearings and has the same problem. If the thrust bearing falls out, it's very bad news, like connecting rods going through the side of the block.
Vapor lock was a big problem my car had. I believe it was '78 or '79 there was an improved fuel pump that included a thick insulator to help insulate it from the hot engine block. Most folks I know get a Facet electric fuel pump, mount it just in front of the gas tank, and either leave the mechanical pump in the fuel line or bypass it completely.
I think most folks use 155-80R13 or 165-70R13 tires on them. The original tire is a 145-SR13, which translates to a 145-82R13. Good luck finding those. Don't go wider or you'll be scrubbing the sidewalls on hard turns.
Watch out for rust in the door pillars and the side rails.
Otherwise, they are a blast to drive, because they are small, extremely nimble, and pretty zippy.