Jawaban:

I'll prefer "How can I afford it?"

Penjelasan:

Why? because if you choose "I can't afford it", you have failed mentally and that negative energy will make your brain telling you to stop trying because it makes you think that it is impossible to afford something that is actually possible if you have the right mindset.

If you choose "How can I afford it?", that means you are willing to try and your brain will start thinking on how to afford that thing, that makes you either telling yourself "It is affordable!" or back to "I can't afford it". But still, I'd rather choose this one over the negative one because you never know what you are capable of.