"I can't afford a new suit."
Translation:Dw i ddim yn gallu fforddio siwt newydd.
I think it's good to accommodate people who did not start the Duolingo course with zero Welsh, but who already have some knowledge that they want to refresh and expand.
I'd use fedra i ddim for "I cannot" by default as well, based on what I had learned previously.
So thank you for adding it :)