i've used them since 2003.
you really just need a bottle of the clear coat wax, two bottles of the gloss spray (You'll dilute it with 50% water, so you end up with 4 bottles) and two bottles of the car wash.
The above recommendation will last you one to two years, depending on how frequently you wash. The wax will last 6+ months, so it's not done that frequently. Car wash can be done weekly... once the vehicle is washed and dried, the gloss spray cleans it up (removes water spots too if you have that kind of issue).
I personally would double the above order, since there is a flat fee of $9 or so for shipping. You can always buy the zaino recommended set of products, but I ended up with wheel gloss I never used, leather cleaners I didn't need, and too little of the stuff I actually used (gloss spray and car wash)