Hey mate!
Great units, I've had the 650 for a few years now and very happy with it.
I agree, you're paying big money for the genuine maps. There are refurbs going around for cheaper ( I think you ran into just a dodgey dude) but I'm not sure if you buy a refurb if it voids the warranty (on the unit)?
I personally use the lite version of the topo maps which is cheaper($89) however has 20m contour lines instead of 10m! (I think! at work so I can't check my unit At the moment )