What got me started is one day I organised my tools and hung up my 4 shifters on a board with 4 screws. I noticed I had a 15" Bahco, a 12" Bahco and 8" Bahco and a 12" in another brand. Seemed to me a good idea to sell this other 12" and get a 10" Bahco to make a set of Bahco in size order - an 8, 10, 12, 15. I did that. Then I found out I could get an 18" and a 4" and a 6" to make a fuller set. I did that too. I noticed while I was acquiring this set that there was a lot of variation in labels and age. So I read about Bahco history. Then I wasnt happy having one set of each size, I wanted a set of each type in each size. So I kept going. Fortunately, or unfortunately, the variations are almost endless, so I can keep getting them without having any repeats.
How many will I need before I absolutely have one of every variation you ask? Dunno. 50 is not near it at all, nor will be 100. It could be 250? That is just a guess. But collecting is not about getting to some end goal. If these shifters were freely available and I had lots of money to buy them straight away, what would have I achieved? Surely its about the process - the journey - and learning along the way.