Is there a quick way to get credits when I have no more missions to do?

[Indurok]

I completed the game and its DLC, and there are two items left to buy at one of the terminals on the Krogan planet. But I don't have enough for even one of them. There are no more missions, there haven't been any investment opportunities at the Shadow Broker's bass for a while now, I've discovered every planet and done whatever missions were available on them, and I am not so willing to spend a ton of hours earning little by little betting on Varren fights.

[COINCELPRO]

use console commands

[Dethlane]

Use ME2 save editor

[delta]

You don't get enough credits to research everything. If you're willing to cheat, then use the save editor. I actually do recommend doing that, because I really, really, REALLY hate planet scanning.

[ModerNertum]

Planet scanning is so boring. It made me miss the Mako (but you do need to do it to have better Normandy War Asset on ME3). If I knew what values were exactly for that outcome I would have already edited saves to make it happen.
For credits maybe try a new game+ (with ME2) after completing achievements or make sure to have a ME1 imported character with thr Rich Achievement. Thats the methods I am aware of.