Wanted: Rear Hub & Small Chainring for polo.

The On-One hubs are pretty cheap and decent, combined with a strong rim they'd be perfect for polo.

A 19h rim sounds odd and weak though, hmm.

I can't see 18 spoke wheels lasting too long on the court

Fair point. I'm having to take what I can get at this stage of the game however.
Perhaps I'll put some disks on them then.