I started looking at this a few years ago, and found a set of books called "the bowyer's bible"
It was an interesting read because it covered a lot of history, but also a lot of technical how-to.
The best part was a section on making bows from wood you purchased at lumber-yards.

While I am sure useing purchased or harvested staves is preferable, you can make a decent bow from board lumber.

The trick is the moisture content. Kiln dried wood is too dry usually, and I found that just letting it come back to equilibrium with the air didnt suffice.

But if you are interested, find this set of 3 books, and try local lumber yards where the wood has not been kiln dried yet.

I have made 30-40 bows with varying success. I did find that none of my bows could be drawn to the long extents modern recurves can. Whenever I drew past 26-28 inches all of my bows would damage. But I didn't back any of my bows, and I know that can make them more resiliant.

I did have one nice ash bow that drew 42lbs at 28inches. I shot if for an entire summer before a friend borrowed it and it broke in his hands. (I was more embarresed than upset. perfect timing, after I had been bragging about my bow.....)

I think if you develop the knack for making them, then you could purchase boards and just store them in the overhead of a barn or in your bunker with some wood working tools, and have a bow if needed in the future.