Grad School

The cost of Grad school varies greatly and depends on many factors. Grad school is a blanket term that covers people pursuing either a Masters degree or a Doctoral degree, whichever one of these you're pursuing will effect your cost. Other factors effecting cost are: whether you are an in state/ out of state student; whether or not you have need based assistance; whether or not you have been awarded any scholarships; whether the school you choose is a public or private university etc.
If you are pursuing a doctorate you may qualify for a full tuition stipend if you attend a public research university (these are traditionally state schools: UCLA, UofI, etc). If you are pursuing a Masters Degree these opportunities are few and far between.
On average the cost of Grad school (for in-state students pursuing a Masters to completion degree) will average 20k on the low end to roughly 60k on the high end. At a private institution this cost will average 60k to 120k.
I wish there were a simpler answer that I could give you to this question but it truly does vary a great deal.

If you have the opportunity - look for Graduate Assistantships on your campus. Not only will they pay your tuition, but you may also get a small stipend every semester. These positions can be found in various departments from career services to athletics. Having one will also look great on your resume and may lead to a position at the university.

Depends on the school, the subject and the time required. Here is one example:

An MBA can cost about $75,000 - $100,000 depending on the school.

Let's say it is $100,000 and you go full time for two years and give up your current job that pays $100,000.

So, you have paid out $100,000 and given up two years of pay at $100,000 per year, or $200,000. So, in this simple example the MBA cost about $300,000 assuming you have not worked during that period.

Or, you can keep your job and go for an MBA at night and keep your job. It might take longer, but it will cost less in dollar terms, but more in terms of time invested.

This is just a simple example for an MBA. Other graduate schools should be evaluated in terms of time, money and the payback after earning the degree.

Since you tagged this as creative writing, I'm wondering if you mean graduate school for creative writing. If this is what you intend, most legitimate MFA programs are free - you actually get a stipend to teach classes usually. I would NOT go to any program that did not provide you with full funding.

This is totally different if you're planning on attending school for an MBA, law school, or something of that sort, which tend to have better financial payoff.

I actually went to Grad School online through Jones International University. I liked it because it was more cost effective and I was able to obtain the degree at my own pace. Getting your degree online requires a lot of discipline and responsibility on your part, but I was able to work a full-time job to help pay for school while doing my class work at night and some weekends.