Fat Quarters are a bit more expensive, however, as a beginning quilter there are a couple of things you might want to consider:
By all means, buy yardage and save your leftover strips and pieces to build your stash AND Buy Fat Quarters to add immediate variety to your stash.
While the fat quarters are more expensive, you can always find super deals on Ebay. Don't forget thrift stores as a source of stash builders (men's shirts, dresses, etc.) Cut the seams away when you get home and call it new fabric:>)
Welcome and Good luck