I keep an eye out for both the Bell and Polk books on eBay. A Bell "white pages" book from 1954 just sold on Sunday for $184.37 with 20 bids. I have seen some go up to around $300 or more ca. 1880 - 1930. It really depends on condition of course and who's on eBay that week. Back in October a 1940 Bell book in slightly rougher shape than the '54 book I mentioned sold for $77.05 with only 6 bids. It's always a crap shoot on eBay. For my money Polk is the only choice with their added details about businesses and individuals, but I only do general Detroit research. The Bell books can be invaluable for people researching genealogy.