That's a cool workaround, but is an exta $27/month actually unjustified? How much time is lost when people are trying to contact you, and can't, or vice versa?
I did have an incident very recently when I traveled to a part of campus I don't normally frequent and couldn't find an open access point so that I could request entry to the building. I lost at most half an hour finding an access point nearby, and in the future I can walk directly to the AP if the need arises, so it was a one-time cost.
There is also significant one-time savings from an iPod vs. a smartphone, to the tune of $200-$300.