Surface starts at $499. I usually suggest the 32gb surface with a touch cover for $599. Most smartphones anymore have a hotspot feature, or as someone pointed out, Wi-Fi is almost everywhere.
Good point bringing up the Pro v. RT. The RT only runs apps from the built-in Windows Store. It is quite extensive already, and truly does grow daily. If you have questions about a particular app, feel free to ask and I can check, or swing by your local computer shop and check it out on a Surface or Windows 8 machine.
Another few things about the pro v. rt.. don't take this as putting down the pro, it will be a great rig for many people. I just don't think it has its place in the field yet.
The battery life will be about half as long as the RT (around 4.5 hours)
it will be about half as thick again (I believe around 14mm.. still very small for what it is)
the price will be starting at $899 for a 64gb machine
The RT has done everything I need so far, I haven't used my laptop since I bought this. The cloud storage integration is great, I have all of the files on my surface, in real time, as I do on my home computer. huge for me.
the number one thing that is killer for me is the Office software built in. Not a day goes by that I don't use this. from billing to taking notes (i'm in hort. school right now) to writing papers and even making up powerpoint presentations to show to (potential) customers, it has been killer.
If you want to check out a surface, head to your local Best Buy, Staples, or if you have one in your town, Microsoft Store. Word of warning, if you do head to BB or Staples, take what they say with a couple grains of salt. I was lucky enough to receive over a month of very in-depth training from Microsoft about Surface and all the rest of the stuff we sell, where I bet those guys might have heard a 3 hour lecture.
again, if you have any questions, please ask. I really do like the surface, and i'm lucky to know its uses in our field