Why give yourself this headache though?, the seatpost is a thin diameter if I remember correctly. I wouldn't want to be faffing about trying to get an obsolete sized seatpost from anywhere. A bike builder will want to be making their money on expensive builds not messing about with making a seatpost for peanuts.
Maybe I've misunderstood?
I thought he had a perfectly good bike that needed a new seatpost but he couldn't find one anywhere and its an odd/obsolete size.
If I was in that position I'd ask a bike builder or metal worker (who knows) if they could make something the right length/shape/dimeter rather than scrapping the bike. Worth asking.
Either that or keep it as my 'out of the saddle bike!'