I don't know much about wheel balancing in general, but it's not exensive to have them balanced properly. However, mwsint.com who are the supplier of the wheels to the M3W have a nifty, albeit expensive, thing to do balancing of wire wheels in ordinary car setups. However, you should be able to go to a motorcycle outfit for this, even for a 15 inch 4-wheeler.
Balancing wheels aren't expensive:
Nifty thing (read why it is important to have the wheel hung like it is on the car):
http://shop.mwsint.com/product_details.asp?id=1041Balancing wheels:
http://shop.mwsint.com/productslist.asp?catid=70&pagenum=1They also have some information on the various wheels, tyres etc. which reads so even someone like me understands it.