You should not have a hard time finding it on the internet. There are loads and loads of sites dedicated to selling music. Just figure out what your desirable difficultly level is, pick a set of songs that you want and use Google to locate a seller. You could do it in an afternoon.
If you're looking for any type of sheet music I'd recommend looking well in advance. It might not be too difficult to find but you might end up having to order it online if you don't find anything at the store and that can take a while unless you pay for fast shipping.
Finding quartet sheet music is easy. You can download scores and parts from the internet, or order them from shops such as Shar, Dover Publications, and Frank Music Company.
