Assuming you're talking about GTR's, R33's don't cost 1/3 of R34's...
R33's start at about $45K (not sure why the one Motorex has is $80K though), so it's more like 50% of a R34 (RB Motoring had a few R33's not too long ago) and I don't think you can get a R32 GTR for $25K, you could get a GTS for $25K, in fact Motorex has one available...
http://www.motorex.net/stocklist.html
Not sure why you would want a R34 without the engine, although (if I remember correctly) I read that Top Secret put a VQ30DETT into a skyline and I think they were racing it in JGTC or something like that...