Inflatable bounce house or water slide?

[Orsyah]

I want to buy an inflatable bounce house or water slide for my kids for this spring/summer, but I can't decide which I should buy. I can only afford to get one and I'm looking at spending under $400. A few questions I'm wondering about:

-Do the water slides add a lot to your water bill?
-Would it be too hot to use a bounce house during the summer? We're in central NC where it gets pretty hot, but then again we could set it up in the evening instead.

We don't have a lot of options for summer entertainment in our area and a membership to the local pool is $350 for the summer (you can't do pay as you go, you have to buy a membership) so I want to get something the kids can do at home. And I'm anti-trampoline so I thought a bounce house would be a good option instead.

Any thoughts or experiences?