Cost me about 350 to get the car picked up from ballarat, sent to sydney, then sent to adelaide. Place called Adelaide Car Express are your best bet, they are cheap and professional. Shipping cars from syd-SA is relatively inexpensive as we got most of our cars from sydney ports.
And yeah.. I am testament, don't buy a really obviously modified car from interstate. If you get one and need help standarding it up, I can give you a hand.
Easiest way though, is to get a post office box in the state you're buying the car from (haha any modded car owner would help you screw over a transport authority) and get the rego transferred interstate, then you don't have to take it to regency for a VIN check.
That said - the day I went to get the VIN check was a bad day for it, there were cops everywhere, and someone got sent to regency for window tint, normally the guys at the VIN check place just tell you to take it off, and get you to rip the corner of it. (according to the skyline people). The VIN check is not a roadworthy, and they could have done me for a lot more than they did, but they chose easy stuff like the steering wheel etc.
Edit: Also, no offense to the other owners, they are all winners, but amuldays (last link) is the pick of them.. although fyfeys will probably require no work to go through the VIN check at all. But, heh, the money you save will not go far towards mods...