I only have about 140 netsuke, so I would be classed as a small collector. I do know that the recent US ivory laws, principally under Obama, have pretty much side-swiped the Netsuke collecting market there, and people have lost millions investing in them. Europe has also been strongly affected. Last summer I heard that even for example selling in Paris and collecting the payment into the UK can bring on a fine of up to 250,000 GBP.
As to the Netsuke above, I doubt that it would be possible to prove over 100 years old. But it is legal to own, will not be crossing state borders, and as Moses says, it is a family keepsake, so all is good!