So, Platinum Nacet you say ?...My guess is, they are an already existing blade, branded KCG. I wish I knew which one, so that I could get a cheap 100-pack.
Best I can factor is $.45 per KCG bladeSame here, the KCG is my favorite and most dependable blade (although it can be rougher on the neck compared to my other blades). I went into DE shaving in December 2021 (with a KCG and 3 packs of KCG blades from the local pharmacy store) and managed to stock up just shy of 200 blades for approximately 0.30-0.35 cents per blade (but currently they go for around 0.50-0.60 cents a blade which is ridiculous). Seeing as they can run for 10-14 shaves easily (but I must admit, I usually retire blades after 7 shaves) the cost per shave are very good.
I have seen other threads, forums, reviews and even mircoscoping comparisons of the KCG and other Gillettes. From my understanding the Nacet (difficult to get in the Netherlands, but roughly €0.40 per blade) appears to be the closest, but Gillette Premiums (€17 for 100) are also mentioned quite a lot. I do not have those blades in stock, so cannot say anything out of own experience.
And as with everything shave-related: YMMV.