I think that 4500 is way too much, unless of course it's in mint condition. If you are looking for a track bike only, there are ways to look into. If you are looking for a titled MC18 though, well maybe the price is easier to pay, considering there aren't many in the US (I think).

I am about to get my R5k, that's also dismantled, (some parts missing), for approx. 450$.