|8||1187 XP, $22, SDU Weapon Equip Slot|
Run over and talk to Jessup to finally be able to enter Sanctuary, which will be a safe haven for a long time. Sanctuary is a big place and has a lot of things to do, but most of it is locked for the time being, so roll along with the mission. The first thing you need to do is visit the town's mechanic, who resides in the big garage as soon as you enter (he likes Pimentacos). Talk to him and he'll hand over some Eridium, as well as direct you to fetch two fuel cells.
Note: Eridium is resource that is used in a variety of ways throughout the game, with one immediate use being the Black Market to purchase more inventory space and more ammo capacity for guns.
Both of the fuel cells are in the garage and once you have them, you can install them in the center of the town. Install the first two, then head to the Black Market to get another, although you need to purchase any of the items that Crazy Earl is offering to get the fuel cell (best to either get an upgrade for one of your most used gun types, or just the Backpack Upgrade for more inventory space).
Install the final cell and Scooter will attempt to make the city fly, only to no avail. Scooter mentions to go to Roland's place in order to find an ECHO left behind, so talk to the man standing in front and get the key from him. Head inside and check the ECHO on the desk to finish the mission.
Sanctuary is an important place in the game, since it serves pretty much as your hub. There are many things in this town that will help you in your journey to stop Handsome Jack. The Black Market sells permament character upgrades, such as more inventory space, increased ammo capacity for all weapon types, and even more storage in your bank.
In the same building as the Fast Travel Station is a golden chest. To open this, you'll require a Golden Key, which is sort of like a premium feature of the game (minus having to actually buy them with real money). If you look at the official Borderlands Twitter, as well as Randy Pitchford (@duvalmagic) from time to time, you will see something called Shift Codes. On the game's menu, you can put these in to get the Golden Keys mentioned above. Note that there are also other sites that compile these, in case you miss them on the official channels.
Back to business, the golden chest will offer two items for you, which will always be of purple rarity. The items will always be at the same level as the person who opens it, so if you're level 10, you'll receive level 10 items. Also, Relics and Class Mods will not be offered if you're under level 15, but everything else can appear in the chest.
Inside of this place are two slot machines that you can gamble your money on in some free time. The cost for these slot machines will increase as you complete more of the game, and you will be able to get money, weapons and even Eridium as prizes. Just be careful of the three bandit heads outcome, as this will produce a grenade, so you better step back from the machine.