If they are real then you have got yourself a bargin there.
Are they Monza IIs, as they don't have a diamond cut finish or the darker grey paint on the insides? If they're just Monzas then I didn't know you could get 18" variants?
Even if they are genuine, surely the fact they aren't 2 tone and diamond cut means they lose most of the appeal of having Monza IIs? You'd need another £400 to get them looking like new.