Second chances sometimes work out in life, but they almost never do in philately. The 1930 Zeppelin stamps were issued in 1930 and their high face value during the Great Depression meant that many collectors had to forgo buying them and that many people who bought them could only afford one set and not put any away for future sale. Prices of the 1930 set rose quickly after they were withdrawn from sale in 1931. So when the United States Post Office announced in 1933 that they were giving collectors another chance to buy a stamp that seemed certain to go up in value (and at a significantly lower face value than the first set) collectors lined up for the largess. So much so that the Baby Zeppelin ( Scott # C 18) has been a bit of drug on the market for the last eighty years. The stamp moved up in price steadily from its 50c face value to a few dollars each in the early 1960s. It enjoyed a significant run in the late 1970s, when all stamps went crazy for a while, briefly flirting with $250 each.
But the #C18 is a common stamp and as collectors have become a bit scarcer, its price has dropped. Today you can buy a perfect one for a little under $30 on EBay. And you have lots of choice too. There were over 800 for sale on EBay as I wrote this morning and we just sold a stock of over 300 nice ones to a wholesaler for $6000 or $20 each. Though the past 80 years price increase for the stamp has averaged a bit over 4% (the regular Zeppelin set #C 13-15 has had an annual growth rate of a bit over 7% per year), the future seems less sanguine. When quantities of nearly a thousand of an item are for sale at any time it means that you will never have trouble buying one and that you will have trouble selling yours. So buy all of the more difficult to find stamps first and only buy your Baby Zepp when it is the last stamp you need.
