On my Common App, I said I was going to take 5 AP exams, but due to financial problems, I had to choose one not to take. Do I need to email all of my colleges about the change in plans?
I don’t think so. You still took the class. The thing AP scores are used for is credit, and then only if you send them. They won’t know or care to know.
Nope; for admissions purposes, they do not care. As long as you perform well in the class, you’re fine.
Is there any way you can try to come up with the money such as working odd jobs? APs are typically much cheaper than comparable courses in colleges or universities.
I would if the AP course counted for credit at my schools but it doesn’t.
You don’t need to inform colleges. 
Relax.