Thanks. I'm aware of the ammo issues as it has been near impossible to find some handgun calibers. Fortunately, I keep quite a few thousand rounds as backup.
Eventually, I expect prices will calm down -- and it will probably be close to a month before I end up buying a rifle -- or at least a few weeks.
Other than 223, the candidates I'm curious about are .17 HMR, 7.62 x 39 and 7.62 x 54r.
The above seem to be the cheapest calibers, though I imagine the latter two are less available. .17 will certainly be the cheapest, but I expect I'll not be satisfied with the range... I am, though, considering it for a start.