Stuck on Chapter 6, help with the plat trophy

Hello!

I love this game and I'm replaying after my 2021 run, this time aiming for the plat trophy on Steam.

I know we need at least 8000 credits for the Nova Corps fine paid achievement. I chose to sell Groot and got into Chapter 6 with 12k

The thing is I'm also aiming for all collectibles and I'm extremely confused about which ones I can buy there in order to still have enough credits for the fine and get the plat trophy in one single run.

Any tips on how to do this? I already messed up my save file (I was left with 2000 credits) and I'll need to replay chapter 5 now, lol.