That's not exactly how it works. Professors can use grant money to buy out of teaching; they are not forfeiting their base salary. That money will be (indirectly) used to fund other instructors, which may be grad students. It's not like the department head forces an unsuspecting grad student to teach; if they choose to teach, they will be paid for their teaching (tuition + stipend) so that they do not need to be funded by their advisor's grants. The money has to come from somewhere.

You don't always get paid--a lot of programs require 2-3 semesters of TA duty, even if you don't need the funding.

That said, I found teaching to be pretty fun and helpful in solidifying my own understanding so it was helpful (but I'm sure the school also likes the free labor).

So, the student gets the class at a discount?

Typically the student gets their classes for free, plus a stipend on top of that.

I think they meant, "Does the 'undergraduate' student get a discount for a class that is being taught by a Graduate Student rather then the original faculty staff".

As everyone here knows, NO.

Fun fact: buying out usually means "use grant money to cover hiring an adjunct for a term," not forgoing salary. Adjuncts are cheap (they cost less than a grad student, since they don't get benefits), and a successful research semester tends to make that money back with interest in overhead from the next grant submitted.

Who said a grad student gets benefits? At my college at least, grad students are basically students with - if they're lucky - a stipend and a tuition waiver.

A student can buy into a group insurance plan, whereas a contract worker cannot.

Oh I see, thanks for the info.