to be fair if you want to buy one then go for it. they are high cost to run but you will find a way to pay for things if you love having a supra as much as most of us here.
cheap turbo kits are improving on quality and more and more people are saying they have fewer problems, but its still considered a custom conversion and there will always be niggles like something not fitting perfect with any custom job.
depending on the cost of the car, if you have a friendly mechanic you can buy and turbo an NA for good condition TT, but it isnt proven to be as reliable as it normally isnt.
but then it comes down to cost, if you save for a TT then you have that period of time waiting to drive it, if you think your be happy with the NA speed you can always save while you have a supra. if its going to take an extra year to save money for the difference of a TT rather than an NA, would you rather drive a NA and turbo it down the road, even if the total cost comes to having a TT. id rather have a year of driving plus most NA-T's are rated higher bhp than some stock TT's.
but then you have a different gear box ! i know when i go NA-T i'l always want a 6speed instead of 5, just something il have to live with.
supercharging ISNT easy, and its uncommon so there isnt a huge amount of info on it. but saying that, a supercharged supra is DAM friggin awesome