It looks like DealExtreme is finally selling batteries for the S10.
So far all they have is a black 6-cell, but it's only $48.
One thing I noticed, however, is that the feet look different than all of the other non-OEM 6-cells, so it might be from a different manufacturer than the batteries on eBay.
I'd bite the bullet and buy one to see how the quality is, but my S10 is white. Hopefully they will start selling more batteries for the S10.http://www.dealextreme.com/details.dx/sku.22495