I was recently at a Flea Market and saw a very old family Bible sitting on one of the shelves. I understand that some people are willing to sell anything to make a buck, but instead, think of the historic value of the family Bibles. Since some of them may have the only recorded information for births and deaths, especially if they were in a new settlement without a local government.
Instead of throwing them away or selling them, think about donating them to your state's archives or historic centers. They will input the records and preserves the Bibles in good condition.