I don't have the fundamental kit but I do have "Gaining respect and control on the ground". It helped me a lot. If you don't have your horse respect on the ground you sure won't have it in the saddle.
What helped me with my riding and understand what my instructor was trying to tell me was reading and asking questions here. Clinton Anderson also has "Riding With Confidence" and I absolutely love this series. My riding has greatly improved since I purchased this series.
You may be able to find them on ebay
for a fraction of what they cost at downunderhorsemanship. I know I got a great deal on mine on ebay.
If you're going to order them off his website, you may as well become a NWC member. You'll save 200.00 on the set, which is what you would pay for a year's membership.