Crocs is offering 20% off with code with free shipping, MEMORIAL20, for one item. The best deals are in the outlet center, but the quantities and sizes are very limited. It is still worth a look if you need some inexpensive summer flip flops.
Some of the better deals:
Athen Flip Flops $7.99
Grass Roots Flip Flops $7.99
Mary Jane Crocs $9.99
You can check out the selection here.