If you are looking to enlarge or upgrade your 72 hour kit from a simple backpack or 5 gallon bucket, take a look at this link:
If you get it in the blue color (red is much more) and click on the 15% off + free shipping (on orders over $50) banner it ends up being $59.49 (plus tax if you live in a state that does online sales tax, Utah doesn't).
If you are registered on the site and have made a recent purchase you could qualify for up to 20% off + free shipping (on orders over $100). The MSRP on this bag is $200. Ebags also offers free returns.
If you want to add a sleeping bag to you bug out bag/72 hour kit, Amazon.com has had some really good deals on 30F mummy bags for under $50, or you could take your chances and watch for one on Steep and Cheap http://www.steepandcheap.com/