We've only been using Spelling Power for a short time, but it seems very easy and effective! My 2 children love it too! I had heard that you could make do without the student book, but I highly disagree with that! You need both the teacher's manual and student book. The quick start dvd that comes with the teacher's manual was very helpful!
You can order the spelling power edition4 and get CD-rom software with these sheets on it, but the price for this and having it all printed and bound together in a book, is so much more convenient. I would think cheaper as well.