Just a plain suggestion: Instead of upgrading any weapon in the Galactic Store to just the 8th level, why not make it up to the 10th level?
I don’t suggest for a weapon upgrade to the maximum level since it would minimize the fun and work to collect firepower/power-ups, but adjusting the ‘upgradeable’ level of the weapons to the 10th level would probably just be fine (which can be very useful especially on missions with higher difficulty rates/levels).