Cinemasterpieces is David Lieberman. He is located in Arizona, USA. Top notch guy. He is expensive though but that is because he is a dealer. He does have some excellent pieces and hard to find pieces as well but again money, money, money. If you look and since you are looking to buy a gift I wouldn't fork out a lot of money. I am sure you can find what your looking for either on here from other collectors, ebay, emovieposter.com, movieposterbid.com, movieposterexchange.com, or even in heritage auctions. If you are in a hurry then ebay is probably your best bet. Now you do have to be careful when buying on ebay as there are people on there that will sell reprints and pass them off as originals such as John Carpenter's Thing. If you buy on ebay stay away from Tloc. If you look in the sellers to avoid section in this forum you will see who not to buy from. As collectors we help other collectors by telling them who to stay away from and who to buy from. Hope this info helps yeah.
Oh and there is a wanted section on this forum. Just post what you are looking for and other collectors might have an extra copy they might sell or point you in the right direction to getting what you what. Good luck to you and welcome to the forum.