Or you can get Jim to sign your ipad/kindle etc device. That way each book is signed.
If you do this, I highly recommend placing a clear strip of packing tape over the ink, otherwise everyday useage will rub the signature off. I speak from personal experience. I've gotten Jim to sign 2 different nooks, and the first rubbed off so I sucessfully employed the packing tape method to preserve the signature on the 2nd nook (which is also featured in my avatar). I first tried to use nail polish as an enamel to protect it, but the ink would get smudged as it disolved into the polish, so I switched to the tape.
Another choice would be to do this:
(http://blog.patrickrothfuss.com/wp-content/uploads/2012/09/Book-tour-pictures-004.jpg)
(image stolen from Patrick Rothfuss' blog (http://blog.patrickrothfuss.com/2012/09/fanmail-qa-convention-adventures/), be sure to compare the scribbling on her left forearm to my avatar)