Every time my fiancée's sister visits, we make a mandatory trip to Replacements - an incredible showroom/warehouse with the world's largest selection of old & new dinnerware, including china & silver. With an inventory of 13 million pieces in more than 300,000 patterns, there's something for everyone.
The big sell of Replacements is that they will help you fill in missing pieces in your family's china pattern. You can register your pattern or piece online and they'll notify you when some comes into their possession.
If you ever find yourself near Greensboro, NC however, a visit to the showroom is well worth the time. You can browse endless tables of china sets, serving ware, their clearance room of individual pieces, and the "Great Wall of China".
It is also a great place to purchase used/estate/antique dinnerware or utensils. Our house guests Emily & Rob, who love hosting dinner parties, fell in love with this antique set of silver. Too big for their luggage, Replacements agreed to polish it, and ship it to their small apartment in San Francisco.