Master's difficult/expensive to get?

[sanantone]

Meaning you need to pay a lot more and study a lot more as well?

So, would it be accurate to say that master's degrees, at the lowest, cost around $9000 ($250/credit)?

A Master degree is more challenging by design - advance degree/master of the subject. Transfer options are very limited outside of continuing education courses and then you are still restricted by the number of outside credits a school will accept. Term-based schools like Hodges University, Patten University & Western Governors University are significantly cheaper if you can finish in 4 - 12 months.

To complete a master's (Teaching, English) at Western Governors University in 6 months, how many hours per day would that represent (rough estimate)?

It would be extremely hard to do in 6 months. WGU has two types of education programs: for certified teachers and for those looking to become certified. If aren't already certified, you will be required to do student teaching for a semester.