The Primer student workbook sells for $34. You can get the instructional DVD + teacher’s book + consumable workbook for $64.
I never really used the teacher’s book, but I did like using the DVD so that my kids could watch the teacher talking about whatever we were about to do in a certain chapter. “It’s time to watch your math teacher!” and then we’d work on the workbook. Unfortunately, the DVD isn’t sold separately-- a la carte ordering would be awesome.
When you get into the Alpha-Beta-Gamma levels, the price pops up to around $42’ish for the student set, because there’s the workbook plus a test booklet. And the DVD/teacher’s book is additional.
I just got finished ordering Gamma for my third grader to help boost his multiplication, and Alpha for my kindergartener, to give him some extra oomph before he starts first grade in the fall. It was $42 for Alpha (since I already had my DVD from when Big Brother did it) and $88 for Gamma (since I was buying both the student pack and the instructor’s pack).