I talk the Dig and Save up ALL of the time! I find great deals every time I go. You must have ideas in mind as to what you are looking for, otherwise you will be adding to the clutter in your home for sure!
Have an idea of people you'd buy for and sizing. I often buy for friends' children to keep their cost of the next size up at a minimum.
I also do a lot of crafting and try and recycle the tshirts and different materials from the dig and save for my projects.
Have a strategy, and be patient. Pick a bin to start with and go all the way to the bottom and then work down the line either right or left. You'll have a better chance at finding the gems that way.