A few notes here - I ordered this through kprepublic before the group buy showed up here. Everyone's comments are correct - free shipping, but it can take a while to get to you (I'm in US and it took maybe 3 weeks? My previous order took almost 4 months because of COVID).
There is definitely a noticeable height difference compared to my cherry keycaps, enough to where I'm deciding whether I want to keep the Holyoops keycap on this keyboard or not. As far as the build quality and materials used for the keycap itself, the aluminum and silicone build feels high quality and sturdy.