SALEM - As it turns out, $129.99 for a Magellan GPS unit is a deal worth shouting about - loudly - in the Kmart parking lot at 8:30 in the morning.

Salem police were called to Kmart on Route 28 yesterday after customers angrily confronted store management about a sale that hadn't yet started - in New Hampshire, that is.

"There was one gentleman who was a little more vocal than the others," Deputy police Chief Bill Ganley said, explaining that the man had gone out to the parking lot to tell customers entering the store that the sale wasn't happening, after all.

The man, along with several other people, had come for a Magellan GPS unit, which usually sells for $249.99, according to Kmart spokeswoman Kim Freely.

Between six and eight people were complaining when officers arrived at 8:30 a.m., Ganley said, although store personnel said several other angry customers had already gone home.

The problem stemmed from a difference in state laws, according to a Kmart spokeswoman.

Kmart is running a Thanksgiving Day sale today, which will include the $129.99 Magellan GPS, Freely said. But in Massachusetts, where a state law prevents the store from staying open today, the sale was run yesterday.

When Massachusetts' customers saw the sale fliers advertising a pre-Thanksgiving sale, many thought they could get an even better deal by heading north to New Hampshire and avoiding the sales tax, Freely said.

"I apologize for the inconvenience to customers," she said. "However, there's a blue law in Massachusetts that prevents us from being open."

The police were called in large part because of the man who stood in the parking lot, telling incoming customers that the prices were higher than he thought they should be.

"The management just wanted him to leave the premises," Ganley said. "(We) advised him he had to go and could take up his concerns with management, corporate, whatever."

He eventually gave up and left.

But while police don't approve of customers angrily standing guard outside of stores, Ganley said he does think portable GPS units are great.

"I'm a big fan of the navigation systems," Ganley said, explaining that he'd recently bought one before going on a family trip.

He added, "This must be a good sale and people were trying to take advantage of it."