then you're better off sticking with a beige CamryHey, I resemble that remark. Although it's more gold "ish" than beige.
@FoDaddy.
Absolutely understood. But, to call it a fantastic car for it’s day is one thing when compared to others of that time. But, if a car like this were ever sold on the open market under a different name for the intent of OP’s wife, even if you could fit into it all the safety features required; given it’s comparable performance, reliability and repair ease…,it would rank right there with the lowest of the low…The differences are in our minds and the way things were and the memories we have and our fondness for a simpler time and OP’s wife is operating in a fantasy world given her intent for the car. With that intended use…my selected term might even be understated.
Selling it to his “bro in law to give to their daughter” for use or actually “driving it again for herself” with none of your experience or appreciation…that’s not to me, a functional use for eye candy. These cars are absolutely useless unless you have lots of money for either purpose…and in today’s expectations for daily drivers, I might have not been near enough explicit. 
First off, the car is worth more than $7500. According to Hagerty’s valuation tool, the car, in fair condition is worth $12,500. From the description of your car, just getting it running would pretty much put it at that point. A freshened up car with new paint and sound mechnicals would be worth $19,500. This is well worth spending a little time and money to partially restore. Do a full restoration and you are talking $50,000. That kind of work will cost you some serious money, likely more than $50K.
Get it running and enjoy it. Be prepared to spend money to keep it running as these things take waaay more maintenance than modern cars. Or get it running, get it out of her system and sell it to an English roadster enthusiast for $12,500.
It’s called “champagne.”
Mustangman These cars do require maintenance that must be kept up. If it is they can be quite reliable. Also no one has mentioned the 25+ year old tires that will need to be replaced.
All the rubber bits are likely to be in sorry shape, and some plastic bits. Replacing those alone will largely drain that laughable estimated repair budget. Age is not kind to some materials, nor variations in temperature and humidity. All the fluids will also be shot, of course, but cleaning out the gunk could take some patience. So you spend a lot of money and you’ll probably end up with a car worth what you spent on it, but not a car anyone in your family has felt any need for in decades.
If the young woman in your family finds this car appealing, sit down and talk over the pros and cons. You’ll have to do some research to find accident and fatality rates for a TR4 and for a typical modern car, preferably one she likes. List features the two cars have. Make sure she understands you roll your own windows, lock the doors by hand, and don’t have power assist on brakes and steering (probably - few roadsters of that era did). She needs to understand that the heaters may not do a good job keeping the drafty cabin warm and the roof may leak. The roof provides no security whatsoever, so never leave valuables in the car. Don’t install a visible upscale audio system, either, as these are also easy to steal. Let her know that cars like this can have unforgiving handling. They’re so light they can be great fun, but take skills you don’t learn driving most modern cars. Suggest that an advanced driving course would be a very good idea, not just so she can drive this car safely, but to learn lessons she’ll be able to apply no matter what she drives.
Hope this gives a few ideas. I wouldn’t want a young family member driving such a car, but proper preparation can reduce the risks.
OP: If you’re interested in selling to the public, I would be a buyer. Sounds like you folks aren’t sure, I hope that you make the right decision for you. I’ve been an owner/fan of stuff like this for years, and I believe that your numbers for restoration and ease of use are a little off. This is a really cool car but IMO will take a lot of money, time and love to restore. It will also be a bit of a challenge to drive (these days since we’re now used to sports cars like a Miata, they don’t break down). The “Prince of Darkness” Lucas electrics, early and often valve adjustment and valve jobs, leaky tops, hard to acquire parts, will present many challenges but I still envy you. I’ve owned/own several specialty cars and it has to be a labor of love. Good luck, sounds like an exciting time for you folks either way! Rocketman Oh, one more thing . . . would you mind posting a picture, it would be neat!