"Sa a two che". That is too expensive. Sometimes there is an "a" after "sa", and sometimes there is not. Why is this? Mesi.

Sometimes we tend to swallow that trailing "a" and it gets lost into demonstrative "sa" and, all you see is "sa..." instead of "sa a..."
Here's a link that will help to answer your question: Demonstratives

Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words