Translation:I want a new pen.
Please see previous comment 'should like' is more polite than 'want' in English English
No one i know uses 'should like'. It sounds very pretentious. 'Would like' is the usual more polite way of saying 'want'.
Does anyone know if 新し can be used both fot things that are brand new as in just out of manufacturing and never used as well as things that are just new to me, as in just a different pen?