A somber flag ceremony marked the opening of the National September 11 Memorial Museum in New York City on Wednesday.<br/> <br />The museum displays a wide range of artifacts from the 9/11 attacks, which killed nearly 3,000 people in 2001.<br/> <br />But it's the gift shop of the museum that is causing controversy.<br/> <br />Some, like Helen Hatfield, think it's unfair to sell memorabilia at the site of such a great tragedy.<br/> <br />(SOUNDBITE) (English) HELEN HATFIELD, 9/11 MEMORIAL VISITOR, ALSO FROM TEXAS, SAYING:<br/> <br />"I don't think it's a good idea for people to make money off the memorial. It's a tribute to the people who were killed here. And I just think that would cheapen the value of the memorial as a whole. And we want to think about the people, not about souvenirs or making money or anything like that."<br/> <br />Others take issue with the price tag of some items, like a wool scarf for 95 dollars or a plush toy dog for 19.95.<br/> <br />But museum organizers say the gift shop is necessary to fund
