If the TOS bothers you, have whoever your isp is install a second connection at your place, and have your inlaws on that account. I don't think the isp would have any problems with that, since they are gaining another customer they otherwise could not have.
I am shooting 7 miles on a hop for internet. I highly recommend SMC2891W-AG. This model has the built in antenna for the a band, and is working very well for us. Price is around $600-700 dollars, so its pricey. However after running the radios for 14 months now, I have never had to reboot or touch them. Rain, wind, fog, dust...nothing seems to affect our signal, and I have used it during some pretty torential downfalls. It may be too pricey though, but if reliability is a factor, I give these radios a thumbs up.
If you are looking for something less expensive, check out the radios made by Ubiquiti. I have a set that has been operating around a month, no complaints yet. They seem to be well made and the interface is very user friendly. They offer both A and G models for under $200. Good Luck!
Update: I see the link you posted is an Ubiquiti. I would recommend 5ghz A band over the G. I have had fewer problems with the band. Just make sure you have good line of sight.