Depends on what you include in the realm. I include things like hatchets and axes, saws, and multi-tools.
Just like with every hobby I'm involved in, I get bored rather quickly. I buy a bunch of stuff right away, enjoy a little talk about it while soaking in an enabling that I didn't need. Then I over do it and move on realizing I don't really care that much about it. I give a bunch of stuff away that I never should've bought in the first place, but I got a great education about something cool and manly in the process, and there's no putting a value on that. Or at least that's what I tell myself when looking at my savings account and realizing what it could've been had I just stayed away. But, as always, I digress.
As for how many, 8...
A primary fixed blade with a solid backup (2)
A primary folder with a solid backup (2)
A multi-tool (1)
A hatchet (1)
A collapsible saw (1)
A machete (1)