http://www.landandseawifi.com/products/wavewifi-rogue

I see that the current price is $350.

This system has been perfectly reliable for us. It has a range of up to a few miles. For example, we were a couple miles of Nanaimo (Vancouver Island) this summer and picked up scores of wifi nodes and one usable enough to send a quick email. Most nodes are locked these days. The antenna is often handy when we are in marinas with a weak signal. The antenna makes all the difference.

There are cheaper solutions. Why did I go with this one? It uses power over ethernet, simple cabling, an interface box and the output is good old ethernet. You don't need to install any software. You simply go to the TCP/IP address that it assigns itself and look at the list of nodes which are sorted by signal strength, strongest at the top. Very straightforward.

It comes with both AC and DC power connections.

The antenna mount is a bit bendy but has survived so far.

There's probably a law against using someone else's wifi. At least I don't stream video on these open nodes. When in a remote location, one must also remember that the node might be using incredibly expensive satellite based wifi. There is some honor among thieves after all!