I think it depends where you live. In AZ they are very common and $65-$150 for a day. I was talking to other Nesties in WA and MI and they are over $250 per day.
It may be worth buying one. We just bought the Little Tykes Jump and Slide for $170. It is really big, and is well made. I see years of jumping enjoyment in our future!
I was pleasantly surprised when I called about one for DD#1's birthday party. It's a Disney Princess one fairly big that's $99 for the day including delivery, set up, tear down, etc. for as long as we want it that day. I was expecting more. I know they're more up in the north east...
Re: Cost Of Bounce Houses