I would say that 75K, for the first suit would not be outrageous. In fact, working in L.A. might even be on the low end. You got shop rental, utility bills, a crew to pay. Real estate in Cali, aint like the midwest. I know of one guy who worked on the fast and furious cars, and it takes 80K a month just to keep that buisiness from going under.
I'd say that most of it comes from general overhead and labor. Also not mentioned is that the actor was bodycasted, and then you have to make a bunch of copies for everything from running foam latex, to sculpting, to finish work on the suit, and storage. then there's the foam, you run foam constantly. On a suit like this it's not ness. to use silicone, because seams will not show. but things can be much cheaper if say, I did a suit like this with no real deadline, and outa my home, and hired no help, which I never do, It would be fairly inexpensive, mostly just the time.(2-3K for one suit)
Great thing I like about this suit, is it's forgiving. unlike the later batsuits which I have ran in foam, uber pristiness is not an issue. That's another thing that can keep costs down, not having a suit that requires uber uber pristiness. sculpting is quicker, flawed foam pieces can be fixed, seams aren't an issue, even rips can be repaired to some extent.
Durabilty comes from a lot of different points of view when it comes to foam. I've been running foam suits for over 15yrs. In many ways softer foam can see more wear, because it gives into stress easier, whereas foam ran dense, will not give as easy, hence it could rip apart quicker. you can also do a number of tricks to make foam much more durable than the foam just by itself. you can also seal it from U.V. a lotta stuff can be done. but ya, it's a trip into itself, that's for sure.