well, I couldn't get a picture of the alvin, as it's see through and you can't tell that it's against the square of how large the gap.
The two aforementioned lufkin squares - I think in each case, it took me about a week in the US to wait for an auction to close at a reasonable price.
Important thing if you follow this advice is to find a relatively rust free square that shows no evidence of the rule being switched out.
The giant starrett square is a luxury to find at $25, and not something I'd buy if it were expensive (people can be pretty proud of them selling used). The blade of the square is relatively high hardness so it doesn't distort or ding easily. I think starrett would reset a square for you if you had one that needed it, but it wouldn't be $25.
When looking for combination squares, it's not necessary to find a listing that says the head is hardened, just find one with a picture of the head itself with "hardened" written on it. The listings are unreliable, anyway, as all or nearly all of the rules are hardened and sellers will type anything they can find in the heading. Lots of listings that say "hardened" with beat up unhardened heads. The corners of the hardened heads generally look nice and crisp like this one.
Having a good hardened accurate combination square for $35 isn't exactly a waste of money. If you strike a line with one of these squares and then cut to it (or set up a machine fence, etc), no part of the work you do will be wrong at the fault of the mark or setup.
I think I spent about $6000 on steel and wood in the last year, so this kind of purchase here or there seems pretty trivial.