Paul, I got my filter wheel - a motorised Homeyer with True Tech filters -second hand from Gary Beal. Works a treat, but don't know what a new one would set you back. Mike has got the good oil on the various filter wheel options from memory... they're not cheap. Motorised ones are range from around $750AU upwards.
You can pick up cheap manual wheels like the ATik that Mike has a lot cheaper than that though and maybe motorise that?
cheers,