Thank you for playing and for the feedback!
I agree that currently Space mode is very luck based and not much progress is felt if the player has a bad rng. I think your idea of having asteroids drop points could help. Maybe every X asteroids you get 1 point. I'll do some testing and see what number I come with.
The high cost of the final upgrade is because these are supposed to be "end game" upgrades and should take a relatively long time and multiple play sessions to obtain them. On the other hand, the first couple of upgrades are much cheaper to allow more players to access them (relatively) quickly. I think in my tests I unlocked the first one in less than 2 hours of "spacing".
I've seen a player already unlock the 3rd upgrade and it's been less than a week since the update dropped, so I guess they play Space a lot more and/or are luckier with their wheel spins. XD