$400?! That's dirt cheap. I've purchased Airsoft rifles for more than that.
I'd be wary of that weapon. H&K weapons are typically high quality... if you properly maintain them, they'll last a looooong time. CETME must be some Chinese/Chzech knockoff.
edit: CETME is an acronym for its Spanish manf. Here's some info on the rifle:
http://world.guns.ru/assault/as53-e.htm