So far the only source for new cards that I've found is
www.jr.com
They list 128mb cards at nearly $50 each but you might get lucky and get a box of ten for your $50 like I did.
My wife's camera and my 1150 both use SM cards so I try to keep a few around. Over the course of 8 years, I've had 4 or 5 fail and never lost any other type of flash memory. All of those have been older cards or from ebay/craigslist.
Smartmedia cards are much more fragile than other types of flash memory. Follow Nicks "golden rule" at all times. Don't change cards more than you have to and always keep a backup of any books on a card as it may fail at any time. I keep a book or two in the 1150's internal memory just in case the SM card gives up.
I have 13 books totaling 6531 (at small text size) pages on my 1150 right now. They consume 17mb or 13% of a 128mb card.
Michael