They don't cost what they do in spite of manufacturing costs, they cost what they do because of manufacturing costs.
This is by no means complete or probably even 100% accurate (not sure of GMK's process, only another I'm familiar with), but should give an idea of what you face.
Single color dye-subs can be done in a tree as an entire set by a relatively cheap injection molding system, dye-sub them (which is cheap and easy to do) then break off the tree/sprue. You can make the whole set at once in about 3 steps and it's easily automated. Your lettering is controlled by the printer and application, want a new style or color, easy and cheap. Font not sharp enough, you just need to tune it with the printer, ink and application method, once you have it dialed it's pretty easy and while color can shift slightly over time since they're done as a set you won't notice unless you compare one set to another from a later date. You can also pre-mold tons in each color to be dyed later. The bad side is that you can't really dye-sub lighter colors, so it's always a dark color on a lighter cap. These can also be molded in singles, but the bulk would only need sorting by row, not every single key.
Most of the cheap double-shots you see are made one of two ways, either a blank set is made with a thin outer or they're single color molds dipped or sprayed a top coat (sometimes it's just paint), then that outer layer gets lasered back. Note that in both dye-sub and this method the entire set can be shot at one time or in batches of a single key style. This eliminates a lot of the sorting and color matching issues.
Good double shot tends to be one key (or a few) at a time with a multi color injector and then you have to sort them manually unless you invest in some sort of picking system. How many sets do you need to move to pay off a million dollar picking and sorting system? You need expensive molds for each key and there better not be any bleed (start over!), want a new design, you need a new mold, for each and every key and these mods are like art, there's a serious science to making them. Want to change color, each set needs two colors of plastic and you can't pre-mold blanks and add colors later, your color control also needs to be on point as well because it's per key, you do a batch of "T" then a batch of "D" they need to match for an entire set for the entire run, you can't do 500 then have the color shift part way through and just keep going. All of this means tight quality control or it doesn't look good. Basically everything about them is expensive.
Challenges you face? Money and technology. Plain and simple.
If it was that easy to undercut GMK pricing don't you think more Chinese companies would have done it by now? I'm not saying it can't be done, I'm saying it can't be done and still turn much of a profit. That goes double if you don't own the factory doing it and have to contract it out. The one surefire way it could be done is if you come up with some new innovative way to do an entire set of good doubleshots in single pass without expensive molds or injectors and honestly, if you figure out a way to do that there's so much money in that patent that you would never need to worry about paying $100 for a set of caps ever again.
There is one other thing you need consider here.
Ever think maybe not everyone wants them to be cheaper or mass produced? A lot of the GMK hype exists because of the exclusivity. Not everyone can or will spend $100 on a set of caps, giving them something rare. Same with people spending hundreds and even thousands on a keyboard, a big part of it is ego and them wanting something few others have, this is why Cherry red double shot ESC caps were valued at $500 at one point, look at the artisan caps. Some of those people will refuse to buy your cheaper caps simply because they're cheaper and easier to get. How many turn their nose up to good dye-sub thick PBT? They "gotta" have those expensive double shots because, well just because! Ever see people drinking $10k champagne, honestly, is it REALLY that much better tasting than a $500 bottle or even $100 bottle, of course not, they do it because they can and want to show people they have money. You can't really show off a Toyota like you can a Ferrari even if the Toyota will get you to work and back a lot more reliably.
