Presta valves are now my bitches. Evidently you have to unscrew them to blow ’em up. Who knew? (not I, obviously)
Rode over to the bike store, it was closed (some religious holiday, I think; Happy (C2 H5)20). Thankfully a group had stopped in front, including a fellow club member and one of the shop’s mechanics, who showed me how to work the valve. So no money spent (grr), but the tires are now inflatable and inflated (yay).