People at a restoration shop told me a year ago that a full restoration of a TR3 would cost $75,000. I don't know anyone who would pay that price for a TR3, but there are people who can and would pay that if they wanted a "perfect" car that badly.
There is a difference betwen those who have these cars as "an investment," and those who have no intention of ever selling. If it is a car you just must have and "want to die with a TR3 in my garage," then cost is a secondary consideration.
I don't know anyone like that personally, but I have heard of such folks.