Depending on the exact look you are after, you may be best off making a set.
brasswithclass.net has a set of 30" wheels available, if you don't mind spending a few bucks.
Pretty sure there are a couple Amish wheelwrights, on the US side of the line, that could set you up, too.
If you are interested, I can scan a magazine article I have handy, relating to the building of a spoked wood wheel.
If you are looking at the Lee Valley wheels, then I'd figure scale accuracy isn't high on the list. Got a motorcycle wrecker (sorry, "recycler"!) around? A matching pair of either spoked or mag front wheels might suit your fancy. You should be able to use wheels that won't be fit for use on the road, so maybe you can talk yourself a deal there.
Coupla ideas, anyway.
Cheers
Trev