Last year they had a similar propane-powered device on sales @ Home Depot. The thing is though, you have to run the m continuously 24/7 in order to be effective. Coverage is generally circular with limited range so if you hav ea big property you need several to cover it properly. At min you're supposed to have on in the front and one out back.
Having said that, if I owned a house (I live in a condo) I would buy 2 or more. I hate mosquitos. Anything that kills those little f*ckers is a Good Thing.