Hello, I'm trying to advance in the thieves guild on the 360 and I was wondering whether there was a place in which I could steal the store stock that you see when you barter with a shopkeeper. I figured it would allow me to advance quickly in the Independent Thievery quests. Thanks.

Try the upper floor of the Bruma Mage's Guild. The alchemy equipment is owned. Don't get caught!

A word of advice, do not fence more than is required at each quest stage. You could mess things up. AFTER you have done the quest line, then go hog wild.

Since nobody's answering the base question: No, the merchants' stock is normally held in an inaccessible container. There are a few exceptions, but they're merchants that don't have enough to make one worth while.

There are a number of shops that have a decent amount of goods on show, such as the Red Diamond jewelers in the IC Market District, which can be a good place to hit early on. It's lightweight stuff, too. However, a lot of shops have only clutter items of no value lying around where they can be picked up. You'd normally do just as well in a regular home as you would in a shop.

In general, though, you can pick up enough stuff on each quest to finance the next one. Just look around for what shows the red hand and grab some. Food items (especially the more expensive wines) are good, because you can easily dispose of the incriminating evidence, and they always have at least some value. If you don't talk to guards, you can steal ahead of your requirements, just don't fence too fast and you won't hit any problems.