I would use them, but I do understand other people wanting to keep NOS items forever pristine. Leaving eventual resale out of the equation, the only right answer is the one you feel good about.
My four dipless pens all came to me used, all but one with usable nibs, so it's hard to compare directly, and I'm certainly no expert on the market for these. I do know that when I was scouring eBay for one last one so that I'd have one for each base that I already had, I was having trouble finding one by itself for what seemed like a reasonable price. I eventually did find one in green celluloid, but with the nib pretty much unusable ( and it took a lot of soaking before I could unscrew it), and a bunch of unrelated "regular" dip pen nibs thrown in. That cost me $21.60 shipped. I would have been quite happy with the bargain you found, and as I said, would have used the pens (or at least one of them, since that's all I needed).
Edited by ISW_Kaputnik, 18 October 2015 - 02:10.
"So convenient a thing it is to be a reasonable creature, since it enables one to find or make a reason for everything one has a mind to do."
- Benjamin Franklin