No. Websites offering Montblanc pens far below list price and in a wide choice are almost without exception fraudulent. They exist in their thousands, disappear after a short time and reappear under a new name. Order from one and no goods will arrive; hand over card details as well and you must expect them to be misused. Some of these sites distribute malware into the bargain.
The typical signs are extremely low prices, an implausibly complete range including editions that sold out long ago, product photographs copied from other websites, and invented customer reviews and testimonials. Often there is no dependable information about the company's address or about the right of return, or payment in advance is the only method accepted.
New Montblanc stock can be had reliably only from authorised specialist dealers and from the manufacturer's own boutiques. The larger collectors' forums keep running lists of known fraudulent sites; a look at one of these before ordering saves money and trouble.