But Jacobs is not just any collector, and he is not just any 49ers rooter.
In 2000, he was selected by Visa as the team's No. 1 all-time fan, and honored with a plaque that now hangs in the Pro Football Hall of Fame in Canton, Ohio.
His roots with the team go back to the 49ers' not-so-fabulous '50s, when, as a 9-year-old, his dad took him to a game at Kezar Stadium.
That was in 1952, when the Niners had a rookie running back out of the University of Washington named Hugh McElhenny.
The young Jacobs fell in love with Hurryin' Hugh and his elusive, swivel- hipped moves, and with the Niners, a love that has endured more than half a century.
Jacobs said he was "a full-blown collector" of 49ers memorabilia by the time he was 10. His first collectible was a chin strap worn by lineman Ed Henke, but his earliest prized possession was a torn jersey worn by his hero, McElhenny, which was given to him by the 49ers' trainer.
"It was rayon, and ripped apart,'' Jacobs said, "but I had it repaired."
That jersey remains one of his most prized collectibles, along with a 1954 McElhenny helmet ("The old red one with the silver stripe," he said).
Jacobs' memorabilia search got a little easier in the mid-'50s when he began picking up cushions after games, for a nickel apiece, and he then was hired as a vendor at Kezar, selling everything from peanuts, popcorn and soda to programs and yearbooks.
And collecting a lot of those programs and yearbooks, as well as autographs, gum cards, stadium souvenirs, newspapers and equipment.
When he was 29, Jacobs turned his obsession into a business, opening the first of five Northern California and Nevada pro team shops, the Sports Stop.
In 1993, he retired to concentrate on collecting and a new pursuit, writing books about his beloved 49ers.
His most recent effort, "Before They Were Champions -- the San Francisco 49ers' 1958 Season" and "San Francisco 49ers-- Images of Sport"-- are in bookstores, and next year he plans to author a comprehensive guide to 49ers memorabilia from 1946 to 2003, complete with photos and a price guide.
Jacobs knows the audience for that book might be somewhat limited.
"Collectors of old 49er memorabilia are a dying breed," he said. "There are just a handful of us who actually care about the 49ers from the past.
"David Kleinberg, the ex-Chronicle editor, still has all his early 49er collector cards, all autographed at Kezar. Michael Zagaris, the 49er team photographer, still collects old 49er stuff, Clarence Amaral, from Reno, team gear dating back to the '40s, and Jack McGuire, who was a 49er ballboy, has probably one of the best collections around."
Jacobs was thrilled when the long-frustrated 49ers finally broke through and started their Super Bowl run. But his passion remains the close-but-not- quite Niners of the '50s, the teams of Hall of Famers McElhenny, Joe Perry, Y. A. Tittle, John Henry Johnson, Leo Nomellini and Bob St. Clair.
He does have a near-complete run of 49ers programs going back to the team's inception in 1946 as well as a huge store of gum cards over the decades.
But the items highest on his "want" list now are 1946 and a 1947 press guides, and a 1946 program from the 49ers' first game, against the Los Angeles Dons, played in San Diego. Also any ticket stubs from games played between 1946 through 1960; wire and still photos of 49ers; any Kezar Stadium memorabilia, and 49er player uniforms from the 40's or 50's.
"Surprisingly, I just picked up a large Falstaff beer advertising sign showing the whole 1958 49ers team and game schedule in an EBay auction through a 49er collector in London, so it was a rare find."
Jacobs, who turned 63 this year, said that 49ers football remains a huge part of his life, and he knows many others feel that way, despite the lack of recent success.
He's even willing to offer free appraisals to fans who might want to know the value of a particular 49ers collectible.
If you happen to have an obscure 49ers collectible buried in your closest that Jacobs needs for his collection, all the better. He can be reached at P.O. Box 22026, San Francisco 94122, or by e-mail at MJacobs784@aol.com.
