I'm guessing you've probably heard stories about osu players who changed their keybinds every two weeks because "muh wear" "muh freshness" and so on. Pretty sure even some top player did that at some point(rrtyui maybe? I remember reading about it in Japanese). Sure, they won't last a decade, but they're tougher than you think, and you could always solder in new ones anyway.
CMStorm is a very good brand, and I think you may be able to get the Rapid(maybe even Rapid-I) and Leopold keycaps for around the same or less than the 750R.
Also, am I right in guessing you play sprindex? You mention arrow keys, and the chart in the video you've linked looks like a pad chart(but then again I mainly play BMS so I'm not used to upscroll and only 4 lanes, and I'm not even actively playing at the moment).