MILWAUKEE (WITI) — Collecting sports memorabilia is big business these days — but how do you know if you’re getting the real deal? Before you buy a fake, FOX6′s Contact 6 says it’s important to know what can happen. Baseball is America’s popular past-time, and like most sports, baseball has generated a memorabilia business worth billions. “I consider myself very knowledgeable about what a real one and a fake one is,” Mark Mench said. Mench has been an autograph collector for 30 years, and is very confident he can spot a fake. However, his batting average took a hit recently. “A Steve Prefontaine autograph you almost never see. So, he advertised for things that almost everyone would be interested in who collects what I collect,” Mench said. The “he” Mench is referring to is Carl Myer. “The way he fooled me is because – how he spoke. He knew dealers, he knew the business, he knew basically everything I knew about autographs and I`ve collected 30 years,” M