It turns-out that among my three wheels (two plus spare), I have three different rims. I would have to either buy single babymoons for each one or look to use a universal wheel cover (in a fullmoon, likely).
I've sourced the hubcaps from a few places, but shipping is a killer.
I might just go with an aftermarket 'Canadian Tire' fix until I can find time to prowl around a salvage yard or two.
Thanks to all for the assistance and suggestions.
-John and Grace