I have owned single, twin and NA Supras, a few things to think about from what you have mentioned
If you crave power you would be better off waiting to save a bit more and getting a TT, the stock car is a quick car, and not just over 70MPH but through the rev range
If you have a limited budget and it has to be a Supra get a TT Auto as these can be picked up for 5K at the moment (even less if you look hard enough)
If you think you will get a major service, all fluids and 4 tyres for £500 you need to think again, the Supra is expensive to maintain and you must buy the better brands of rubber being a RWD car
The NA is a great drive, I loved mine, but the lack of power is something that will become annoying after time (especially if you stay around this forum for a while !)
The NA is not much cheaper to insure so dont worry about that
The Supra is expensive to look after, especially when you start adding Mods, if you have a limited budget I would get a car that leaves you comfortable with some spare cash incase something goes wrong or you fancy some improvements
I would also consider fuel as the TT uses above the average for a daily driver
good luck in finding the right car, the for sale section is full of good ones