You have a most excellent plan it seems. A good plan is like a road map. If you know where you are headed, you can know what you need for the trip and what it might cost.
Honestly, I think we lucked into a good idea. I had tried to sell my hand made jewelry that I created using my molds but did not sell very much at all. It was a flop but, when we began to sell the molds (which are actually tools) now that was a different story. It seems that folks would like to buy something with which to create their own designs rather than buy the jewelry created by a little known artist (me). TaDa! After the light bulb went off over my head (figuratively), it made great sense.
Your idea of rare wood spinning tools sounds very good. Tool junkies love hand made well designed tools. Waiting a while to open an Etsy shop is probably good. While waiting you would have time to do research on your spinning and find shows, retreats, etc. By the time you are able to begin to sell, you could hit the ground running, so to speak.
In Silver Dollar City theme park in the Ozarks during the fall they have a six week crafters show. People can work in their booth creating hand made tools or spinning, etc. in period clothing. The combination of a spinner and tool making for spinning might get you into the show. Hundreds of thousands of folks attend annually.
Best of luck Susan and hubby! I can't wait to see some of your work and your DH's hand made tools.