So how much did the TM cost to acquire?
One of the few hints comes from Rostenberg's exploration of Hooke's collecting habits. In his diary, Hooke notes: “paid Pitts his man for Machina Boclerus. 35s, Billio Diophantus 5s., 3 pieces of Snellius 6s., Hugenius de Magnitudine Circuli 1s., in all 47 sh.” (Pg. 117) In another place he notes that he paid 7 shillings for his Besson, although we're not sure to which Besson he referred.
So how much was 35 shillings worth? Just over 1200 eggs. And 7 shillings for the Besson? About 240 eggs. Hooke purchased the Bockler in 1673. Nine years earlier his salary had been about 80 pounds or about 56000 eggs. And so, in practical terms, Bockler's book cost him about 2% of his gross take home, not an inconsiderable amount. It's about the same amount as the new fence in my--small--backyard.