GON, or a similar custom, command a higher price for many reasons. Fully programmable, LEDs, both on switch and on board of colors of your choosing. This way you can customize the glow effect on the sides and under the PCB, and on the switches if you so desire. Often the custom housings are specifically designed to showcase these features. The quality of materials used tends to be very high. And of course, like any "brand name" you are paying for the name, in this case being able to have Korean custom, which can be held in high regard.
Bluetooth is great and all, but you still are going to need to plug it in to charge it. Because these modules hold a charge for hours or days vs. weeks or months like a non-mechanical keyboard, it is going to be plugged in more often that it is not. You are greatly limiting yourself if that is a necessary feature. If you are sure you want to go down that path, I would advise not to get a 40% unless you are very, very sure what that entails from a productivity stand point.
