Massdrop often features that awesome set of 1976 keycaps with centered lettering in the photos of their different keyboard related drops, but I have never been able to find that set of keycaps for purchase. That is the next drop I want to see.
chiliNUTYou can always try your luck with getting a secondhand set over on r/mechmarket, but due to the popularity of the keyset and its limited quantities, sets can be quite expensive. The last two I saw were over $500.
nuclear_wizard$500 is nuts! I've actually googled around quite a bit and I couldn't find it at all. Amazon, ebay, aliexpress, wasd, others seem to have 1976 and the similar "hawaii" set, but I've only been able to find either blanks or non-centered top or side prints.
I've never tried r/mechmarket I'll check that out, thanks
chiliNUTYes, you can find the same colorways of many popular keysets ran in groupbuys that quality manufacturers (such as Signature Plastics who ran the original set) made from several brands that will copy the colorway. It is similar to buying anything "designer". Take handbags for instance (I dunno much about that industry, just the only relevant example I can think of), I believe it is Gucci who sells one bag design per year for a high (but justified to the right people) price, then stops selling them. If you want that bag later, you have two choices: buy secondhand verified Gucci bag at a marked up price or a "knock-off." It is similar for these keysets: a groupbuy happens on a website like Massdrop, the sets are made by a quality, trusted manufacturer (Signature Plastics for example) for a "high" price per set (~$200), the orders are fulfilled, then no more are made. That is, unless another group decides to do a buy, but the increasing popularity of new, quality keysets means that the wait time for these manufacturers is long (e.g. the SP Oblivion groupbuy orders that wrapped up yesterday won't go out until next summer). Now if you come along later and like the colorway, you have similar options as in the handbag case: you can buy a secondhand genuine SP 1976 keyset for a marked up price, or if you don't care about getting the "premium" one, go with an imitation set for much cheaper.
tl;dr The sets on Amazon, (most) on ebay, aliexpress, etc. are replicating a very popular set of which Massdrop is using the original (or other high quality versions). These imitation 1976 sets are cheaper, but will not have key characteristics of the original (the large, centered legends, for instance).
chiliNUTobviously the quality and materials aren't the same, but i've known people to make special templates for WASD's custom keycap service, based on 1976, but often with their own changes too. of course it's not the same spherical profile, but yeah. that is an option.
nuclear_wizardI found a nice knockoff set on ebay (I think the brand is called OGKey). The legends are centered, but they are dye subbed instead of doubleshot, not SA profile, and the white letters on the red keys is kinda pink. That said, they were $60 and I'm very happy with them. Also random question since you seem very knowledgable: is there a word for how the caps lock key has a pit/valley on in on certain keyboards? The keycaps I bought actually came with one, but the hole on the keycap that you put on the switch was placed poorly so it wouldn't fit on my poker 2. (https://english.stackexchange.com/questions/418986/is-there-a-word-for-computer-keyboard-keys-that-have-a-valley-in-them-like-ca)