Winkflash (online custom photo book site) is having its flat rate book sale again (seems to do this a couple of times a year).
The deal: up to 100 pages for the price of their "base" (20-page) book with code "ALLBOOKS".
Prices range from $16.95 for a small 8x8 book to $38.95 for a 12x12 book. Shipping is $7 for most sizes; $9.49 for the biggest (12x12) book.
You can make a 100-page 8x11 photo book (so essentially the same size as a letter-sized sheet of paper)for $24.95 plus $7 shipping. =$32.
Window cover, custom photo cover, and leather cover available for extra, too.
I'd describe their print quality as "very good"; paper is not quite as thick/heavy as the paper from Shutterfly, but still feels nice and a good value.
Link: Photo book sale
Alternatively, they offer 50% off their books with code "BOOKS50", which would make sense if you're getting a slim book. No, I haven't tried combining the 2 codes -- their page says you can use one or the other.