Yeah, you start with 30 days off the bat. WoW imo is pretty cheap, it's just the expansions that cost money. But the BC combo is a steal. To buy it all now may be a little pricey with their latest expansion coming out now in three weeks, but the good news is you won't have to buy a new expansion for like 1.5-2 years after this, lol.
What faction do you plan on playing?