Q1. "Is cost a factor in your decision to make sustainable choices?" (1)Yes (2)No

Yes, the question is good, but the measure may not be detailed enough. Since its currently a binary measure, it may tend to sort out the survey participants into neat groups of "cost-conscious" and "not-cost-conscious".

I think gathering data using a 1-5 point scale would be better. If a Y/N measure turns out to be necessary, it may still be possible to convert a 1-5 scale to a binary scale (i.e. values 1-2 = Yes, 4-5 = No...)

So adding to CarolineJankech's idea:

(1) Very Important (2) Important (3) Neutral (4) Not important (5) Not at all important

...which would also mean we would have to change Q1 into something like "How important is cost in your decision to make sustainable choices?"