Do you have access to video cameras at all?
There's two ways to do it....if you can get hold of a video camera that takes a VHS tape and has a firewire output, then you can bring the clips straight into iMovie. I appreciate those sorts of cameras are hard to find these days.
The second option is to find a camera that will take an input from a standard VHS player and has firewire output. Then you can just use the camera as a bridge, with this sort of approach...
VHS player - firewire camera - firewire cable - Mac
I've heard of people in this instance copying from the VHS onto the camera and then into the Mac, but you don't need to do that...you can use the camera as a live bridge (ie, play the VHS straight through into the Mac).
Not the nicest of setups but it saves on any hardware outlays
Phil