I wouldn't be going into this simply for sentimental
reasons but hopefully to make a small profit to
supplement my wife's earnings

You might want to emphasize "small" in profit. It's unlikely you'll
make much more money at this then you would at a minimum-wage job. Of
course, you might not like any minimum-wage jobs so you're left with
pursuing your hobby and making a few bucks at it too, and that's not
bad at all.

If your wife were a specialist doctor to Hollywood stars or a high-paid
lawyer then sure, knock yourself out with a home-based business. But
she's not gonna be making a lot of money by teaching at a reservation.

I do not see very many days left in my 20 odd-year career
as a software designer

Don't knock selling what you already know, there are ways to contract
out programming services from anywhere in the world quite easily.

So, what is the perfect homebrewer store for you all?

I'd say to go for whatever you enjoy the most. If you aren't
sure what you like, dip your feet in several pools and see what sells.
Others here lament the "good old days" of homebrewing, but as far as I
am concerned we're in it right now. Components from 70 years ago till
yesterday are on E-bay all the time, and modern parts are available
over the web in small quantities quite easily. Anyone is free to mix
and match industrial with consumer with military with ham technologies
as they choose - and this is exactly what homebrewers were doing 30,
50, 70 years ago as well, except now we have access to so much more of
all of it!

Tim.