Since he's looking for rims, can we assume he already has hubs? 36h rims would be far easier to find.
Clincher or tubular tyres?
Would it be outrageous to suggest 700c and deep-reach brakes? (Probably!
)
@carpenter 's link is to wheels rather than rims, and 36h steel ones at that, so I guess they're out of the running, but I did find
these.
Not top notch quality, single wall rims, but at least they're alloy and the right size.
Failing that,
bikejumbles are definitely worth a look. Near me, there's an established one in Long Eaton on the 2nd of March and a new one in Lincoln on the 24th. Maybe one coming up in your neck of the woods? Also check
Campyoldy for possible others not on the jumble site.
There are various bike restoration websites, but likely to be more people looking for stuff rather than selling, I suspect.
PS Liking the wooden rims idea!