The Expensive one's ... the 50, 100, 500, 1000, 10000. I saw a full set for sale once and just for the "10,000 dollars" (P-17) they were asking 13,000 USD. My wife thought I was nuts just for looking. In reality, I hope just to get at least the 50 and the 100. Maybe next year or maybe the year after, but I will find get them some day.