I don't know what we are using at work and what it costs, but I can give you a few observations on wide area networking. All our stores are hooked together with dedicated lines. The access speed is in the 1mb dsl equivalent. Since it's dedicated, upload and download is the same speed. I can access computers at any of the locations same as if the machine was in the office beside me.

Performance is not so good though. It works well enough to drop a file on a computer somewhere. I'm very happy with those speeds. But opening a remote file and working with it is much slower. Eg, a spreadsheet that might take a couple seconds to open off the local server might take 15 seconds or more from the remote computer. You'll have to decide if the application you have in mind will be adversely affected by this lag. I've printed to a remote printer, but it definitely takes a lot longer.