I just discovered and purchased this same curriculum for my 3 1/2 yr old.  I'm so excited to use this curriculum with her!  I actually discovered a consignment homeschool bookstore near where we live.  I was able to purchase the teacher instruction guides 1/2 price from there.  Amazon and e-bay also sell the books, but it's not much cheaper than buying from the FIAR website. You could also check around your homeschool community and see if anyone else has used the curriculum before to either borrow or buy from them.  www.rainbowresource.com is the website that FIAR sends you to for purchasing the books. Most people who use this curriculum just buy the 3 volumes of teacher guides (BFIAR and the Bible supplement are additional), then they go to the library to borrow each of the books you'll be reading weekly.  You could buy all the weekly books from the Rainbow Resource Center or Ebay if you want them on your shelf, but the library should have all the ones you'll need if you want to just save money.  Hope that helps.

Thanks Amber- that's exactly what I needed to know!  I'm looking forward to getting started, and I think I'll just purchase the whole thing since I've got several kiddos comin' up behind ;-)