Want a yard sign expressing your support for Barack Obama or John McCain? Be prepared to pay for it.

The $5 price was $3 cheaper than the signs Mr. Obama hawks online, but Mr. Norris, 59, felt he shouldn’t have to pay anything.

Yard signs have morphed from being a simple display of support to an intricate system of raising money and building an online donor base.

When supporters of Mr. Obama and Mr. McCain buy signs or other campaign gear, they also turn over personal information that will be used by the campaigns over and over again. The campaigns even report the purchase of yard signs as political contributions to highlight their grass-roots support.

“In the future you’re going to see a lot of people charged, not because … [the campaigns] want the money, but because it gets you into their database,” said former Texas Land Commissioner Garry Mauro, who led Hillary Rodham Clinton’s presidential campaign in Texas. “If somebody gives you $5 or $10 for a bumper sticker, they will give you $5 or $10 later on. That’s the real reason to do it.”

But many people are willing to pay, perhaps because the historic campaign could make the signs valuable keepsakes.