I bought the smallest model, the full name is Mosquito Magnet Defender. Got it on eBay for about $220. You also need a propane tank (doesn't come with the machine). It converts propane to carbon dioxide, and along with some attractant called octenol, it lures mosquitos near and sucks them into a net trap.
The consumables aren't cheap, you go through a propane tank every three weeks, also change the attractant.
It caught a lot of mosquitos the first month, now there are very few left in the yard. This area is semi-rural with very heavy mosquito populations. I don't even put on repellent any more when I go out by the pond in the evening.
Mosquito fish didn't work for me, my koi hunted them to extinction over the winter!