Maybe I should elaborate more.
Firstly, I would imagine the AE86 Corolla would be way more than any of these other cars simply because of the drift scene going on. They aren't very common anymore either, so that rarity also adds to its cost. I'd imagine its a fun car though.
The 2nd gen RX7 is getting old. Turboed Rotarys wern't the pinnicle of relibility either. Unless you want to fix it every other weekend instead of driving it, I suggest stay away.
240sx Turbo? Didn't know they came turboed, heh. Sorry, no experience with these, no input on this one.
Old Supras are just big boats. Too heavy.
The Miata on the other hand, is a VERY reliable car. The Miata is also a convertible (Might be a bit too cold in Canada though). The Miata is also very reliable even with boost, as its original engine was a turboed engine ripped from another car (323 GTX). You can run 6 PSI systems safely with no change in internals and worries about blowing something. Horsepower rating depends on the kit, and engine you go with. Mods are cheap and plenty available. Aftermarket is huge. There is a reason why its the best selling roadster in the world. Its a small car, and its fairly easy on tires/brakes, even then, the parts are cheap. They are widely available, and you can find some for cheap.
EDIT: If you have enough mechanical skills, you can turn the Miata into a big project car. Feel like dropping a 5.0 in it? Have fun

, plenty of kits available.
If you're still interested in the miata, I would definatly look into the 94+, as they came with the 1.8L, better interior, some extra suspension stuff, bigger brakes, as well as a stronger LSD/Transmission. Even though the 1.6L is nice car, and a bit lighter, the 1.8L is simply BETTER.
If you have any questions about the Miata, feel free to ask.