Assuming that the unlock requirements don't change as more content is added, this achievement is unlocked for buying the following from Rusty's shop...
Every Hook/Lure from page 1
Every Fishing Rod from page 2 (including every upgrade)
Every vehicle from page 3 (including every upgrade)
At the time it unlocked for me I had yet to purchase the licence for Diver's Drop in Old Wreck Bay and the deed for Old Moose Cabin in Old Moose Valley. This suggests that none of the licences on page 4 are required for this achievement but I can't confirm that as I'd already purchased everything on page 4 except the Diver's Drop licence and the deed for the cabin.