So for those, who are having trouble with cheating, I strongly recommend MTool by
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Just go to "About" section and download it. It may or may not be flagged by your antivirus, however I have used it for Hentai Gods know how long and haven't had any issues.
Basically there are two variables, that are responsible for money, one is probably for displaying it on the HUD and another is actual money.
Edit.
In addition to money cheat, you can also cheat items, such as lockpicks. In Variables tab you can find "Breaker quantity" line, it's going to be the third item, what you're looking for in case of lockpick would be two lines above "Breaker".
I'm too lazy to figure out if there is a way to add any guns directly to the inventory or add them to the shop and whatever.