I always found trampolines to be more fun than moonwalks. if you want to invest in an inflatable item, look into the inflatable water slides, preferably 2 lane so you can race. I rented one for a birthday party and it was a big hit.
thank god someone else calls these things moonwalks. i much prefer moonwalk to bounce house. trampolines are fun but make sure your kids are somewhat sensible. <object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/pHYICkt7AF0?fs=1&hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/pHYICkt7AF0?fs=1&hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>
If you want to get your money's worth get a moonwalk slide combo. This one has a removable bumper and attach a pool at the end of the slide. Good for summer and winter rentals.
My in-laws bought one when the grandchildren started coming. It's been a great investment. i'll borrow if for months at a time. It's easy to put up and put away. Great fun for the kids. Makes for much cheaper birthday parties, too.
The one that is really fun has a water slide attached to it, which I definitely recommend you fill with mud. Sell some tickets when you get it, and give me and the kids a holler.