I bought the original iPad shortly after it first came out WITHOUT 3G, and just bought the new iPad 3 today again WITHOUT 3G/4G, and it is rare that I would even use it, not really enough to justify even 1 month of a service plan, even as a GIANT GPS, both of my vehicles have built in GPS screens, and I have a Tom Tom, and an EVO 3D, so, while there has been a rare occasion where I would like to have a few moments of access, it would not be worth the price.
What I really need to do is root my EVO so I can tether. What would be cool is if someone could come up with some sort of "kit" that could be used to "upgrade" and iPad to 3G, but, I suppose there are way too many logistical things that would have to be dealt with such as a SIM slot, and a different rear case too house the antennas, which the batteries are glued to, and the slightly different iOS versions to handle the 3G parts that the WiFi versions don't have, all of which probably make any type of upgrade "kit" impossible. It is a nice thought, however.