Re: I think it was well known....
"The question is, could a "new" Harrier done a better job with modern avionics and technology, for far less money?"
Not a snowball's chance in hell. Could a hypothetical New Super Harrier do all that it required? Sure it could, if you spent enough money - i.e., something an order of magnitute greater on a per-seat basis than the F-35. (Or anything else for that matter.) Most of the cost in producing an aircraft is in the design and development process. To get the cost per unit down to something sensible, you need to produce hundreds, if possibly thousands, of units.
Same with any high-tech product.
Q: How much does it cost to produce one modern CPU chip? Ans: Hundreds of millions.
Q: Having made the first one, how much does it cost to produce the second one? Ans: small change.
Now, if you could sign a customer up to pre-order, say, 450 New Super Harriers and pay cash up front ....