Been there, done that, ....honestly you would be better off buying one that is already supercharged or TT set up if you know that's what you want. It's a bigger cost initially but saves you a lot of money in the long term.
Just for some other info I supercharged my DE at 90-95K miles odd if memory serves. As long as the car is well looked after before and serviced regularly the mileage they have is not as important as you might think.