You can buy the DLCs separate as well.
Gearbox Software and 2K Games have announced a season pass for Borderlands 2, costing $30 and it entails you all the DLCs announced so far. Season Pass is a concept that has gained traction with Naughty Dog heading the same route as well.
If you don’t want to buy the Season Pass, you can always get it individually for $9.99 or 800 MSP. You can purchase the Pass when Borderlands 2 comes out on September 28th. It has $39.96 worth of content and will be available for $30 for all platforms, and oh that’s 2400 in Microsoft money. All four add-on content campaigns are scheduled to be available by June 2013.
Gamers who pre-order Borderlands 2 from participating retailers will gain access to the Borderlands 2 Premiere Club, allowing them to download the Gearbox Gun Pack, a Golden Key, the Vault Hunter’s Relic and an all-new fifth character class, the Mechromancer.
There are a lot of pre-order incentives for the game which you can check out here.