I guess as development progresses, deeper insight into the statistics may become more relevant, for now 'muting' the pop up would be good.
As to the shop, I wonder if, as we are offered three options, would it be possible that you can match one option per tier (Grey, Green & Blue), putting quite a substantial mark up on higher tiers, you could perhaps offer goods that are not yet unlock from the full item list, presuming that the shop engineer has sufficient expertise in the offset, to fit an item the player is not yet qualified. this would also allow you to open new items to the player at a more steady pace if you desire, as the item on rare occasion still becomes available.
edit:- I have my first cruiser 👍