I agree, unless you have the bucks to spend all the solar or other options you find are going to be expensive.
I just got back from the Grand and what I ended up doing after having the same debate and researching all over was buying cheap Chinese batteries from Amazon. They are a fraction of the cost of the brand name batts and most of them had twice the m-ah's of the factory batteries. Most of them come in 2 packs and only cost 6-12 bucks. Worked well for me, I took three cameras; a p&s, dslr, and video.