I cant use internet for games, it uses up too much of my monthly bandwidth. I'd also really like to try the game without using too much of my bandwidth.
Minimum System Requirements for World of Warcraft
Windows® System XP/XP64/Vista/Vista64/7** OS (with the latest Service Packs or updates):
The whole article can be found here
So you need to have in order to play.
With the new Battle.net desktop application you can but you cannot play with other people. It acts like a private server for offline use only. If you cant connect to Battle.net or you cant connect to your internet you can select the "World of Warcraft" game client instead of the "World of Warcraft - (Whatever Expansion)" game client. This will give you the chance to play World of Waraft by yourself but you can only play to level 60 as it is a vanilla with the latest landscapes. You have to start from scratch and even though i said "It acts like a private server for offline use only" you can play it with internet but nothing will be saved from your offline time.