I've got one Bible at home too. Haven't read everything. But sometimes I like to compare things in the Bible with something in the Quran. Also in some books about Islam, there are references to certain chapters in the Bible, then I can read that chapter and know what they're referring to.
Another reason to have a Bible in the house, is when people talk to you about Islam and Christianity, you can show them certain chapters in the Quran and then show them that same topic, the way it's written in the Bible. Also you can point out irregularities and ask them about that. Of course it should be done without insulting anyone. (I have booklets like 'If the Bible had a tongue' by Chaib Bousnana which has very convincing arguments, you can show those kind of booklets and use the valid arguments with people who want to talk about the Bible or want to convert you, when you have a Bible, you can show them the chapters you're talking about)
I had more Bibles too, we had to buy them for school. I had different editions of them. I just have one now and the rest I gave to a book store which sells both old and new books. Maybe you could try to find one in your area. The ones which sell old and new books, sometimes take your old books if they are in an oké condition.
