Back in October, I ordered a G-7700-1 from this eBay seller for $52.49 (see link). Mine didn't come with a Casio box or manual, but arrived in a bubble envelope with a plastic display stand. It appeared to be brand new and still works fine. I see that he has one left for $44.79, which is a great deal. It will have no warranty, but if it works when it arrives it will likely work for a very long time.
New Casio Men's G-Shock Shock Resistant Watch G7700-1CU 79767882686 | eBay