A squeaky saddle can sound just like the BB. Are you out of the saddle when you reproduce it? A way to verify it's the BB or a crank is to get off the bike, rotate a crank arm parallel with the seat tube, and squeeze hard with your hand(s). Repeat with the other crank. You might be able to feel movement, too, as well as hear the sound.

The only other tools I've ever needed for a BB removal (not that I've done all that many) was a heat gun, penetrating oil, and a rubber mallet for tapping the wrench on really stuck ones.

I agree with your plan of collecting tools as you need them. Standards will change over the years, but hopefully you'll get some more use out of them before they're obsolete (or you'll be posting in the classics forum).