I agree with terror in the sense that you missed the boat years ago however I still know plenty of people who enjoy playing today, each to their own I suppose.
Anyway, from the Blizzard Store these are the items you'll need to start off with and I've listed pricing.
World of Warcraft Battle Chest $19.99
Wrath of the Lich King Expansion Set $39.99
Cataclysm Expansion Set $39.99
30 Day Game Time $14.99
From EB games or similar stores these are your prices.
World of Warcraft Battle Chest $28.00
Wrath of the Lich King Expansion Set $37.00
Cataclysm Expansion Set $37.00
60 Day Game Time $42.95
It seems that for some reason, EB have their expansions cheaper then Blizzard's store however the Battle Chest and Game time will be expensive. I'd suggest buying it all through Blizzard to be honest.
Also would it be hard to ask for some people to leave the comparison of your warcraft penis sizes to Xfire. For someone that's simply asking the prices for start up he doesn't need to hear people arguing about when the progressive decline of the games success began. I'm sure he can investigate for himself.
Anyway I hope you enjoy the game for however long it interests you mate, all the best.
Edited once, 28/12/11 - 6:25pm.
Posted on Wednesday, 28th December 2011