PITTSBURGH - Chump change it's not.

A silver dollar that's insured for $10 million and nickels worth as much as $3 million each are among the $1 billion in coins at the American Numismatic Association's World's Fair of Money, which began Wednesday in Pittsburgh.

As many as 16,000 people are expected to stroll through the David L. Lawrence Convention Center to buy, sell or gawk at coins ranging from the rare to the soon-to-be commonplace. Some collectors will buy items that cost less than a dollar and others will make $1 million investments.

The 1794 coin that is believed to be the United States' first silver dollar and two of five existing 1913 Liberty Head nickels are on display. The U.S. Mint also gave conventioneers a glimpse of the designs that are being considered for the next round of special-design nickels.

Kyle Aber, a refinery operator from Houston, Texas, was among the serious collectors and curious who surveyed the approximately 500 booths where about 1,000 dealers displayed their collections.

Aber was looking for two Morgan silver dollars - a 1889-CC and a 1893-S - to complete his set. One of the coins is worth about $20,000.

"My family and friends are supportive, more or less," of the hobby, Aber said. "My dad really didn't understand spending 50 cents to buy a penny."

Aber and others believe coin collecting has become more popular in the last decade, thanks to the advent of the Internet and the popularity of auction Web sites such as eBay.

Like any other collectible, supply, demand and condition are factors that determine the value of a coin, ANA spokesman Donn Pearlman said. A 100-year-old Indian Head penny could cost anywhere from $1 to thousands of dollars, depending on its condition, he said.But an old coin doesn't necessarily make a valuable coin. A 2,000-year-old Roman coin might be worth $25, while a 100-year-old coin might be worth $1 million or more, Pearlman said.But many collectors don't buy coins for an investment, he said."Every piece of money has a story to tell. Money, literally, is history you can hold in your hand. It's either a symbolic representation or a historical artifact of an era," Pearlman said.Although Pittsburgh Mayor Tom Murphy considers himself primarily a stamp collector, he said he collects coins because they are a way to learn about history, other countries and geography."They're not (that expensive) and that's why I like collecting them," Murphy said. "With a couple exceptions, you can put a lot of them together, if you're not that worried about quality."Murphy stopped by the booth displaying the Neil/Carter/Contursi 1794 Silver Dollar.Numismatic researchers and other experts said it's impossible to unequivocally say the coin was the very first silver dollar struck in the United States, but it probably was.Steven Contursi, the president of Rare Coin Wholesalers and the owner of the coin, said it's exciting to see the piece - with its fine details, scrapes and evidence of a silver plug - because of its place in history."This coin is to our economy and international trade what the Declaration of Independence is to our country's freedom: a significant piece of history and a national treasure," Contursi said.With a handful of interruptions, the ANA has held a convention for the last 113 years. Next year, the group will meet in San Jose, Calif.