The International Bible Society (you know, the guys who translated the New International Version of the Bible) have excellent prices and a good selection of different Bibles in indivual or case lots, for as little as 75¢ for a New Testament, or $1.99 for an entire Bible (sans Apocrypha, which was never translated by the IBS). They also have cute little New Testaments for $1.25 a pop in case lots ($1.50 by itself), which were cuter until they decided to make the traditional preface smaller, and add a long section about the story of the Bible in the front, and replace the index of the miracles of Christ with a section on the need to repent. These things used to be just the Bible, but no more.
The reason I don't like the change is because I often give Bibles to people who are already Christian, or to people who don't like having the Bible interpreted for them. Thankfully, the last case lot I ordered was a older stock sold at a discount printed before the IBS decided to add this information.
bibles.com used to have Bibles for cheaper than the IBS, but no more. Catholics may still prefer bibles.com since they do have case lots of the Good News translation with all 72 books that Catholics consider inspired at $2 a Bible. Note that the Good News translation is a very loose translation which emphasizes readbility over accuracy in translation.