At Bob Oyster's Shell station ... putting the price way up over $4 a gallon isn't about making a profit. It's about making a statement to a multinational corporation. After Shell forced him to pay higher prices for gas in San Francisco and jacked up his rent, Oyster says, he decided to fight back. Far from making a huge profit, Oyster is going out of business. He has operated the Shell station at Sixth and Harrison for 22 years, but he's walking away from it at the end of the month. I'm getting nothing for the station,'' he says. At a time when the oil companies are posting record profits, the little guys are struggling to stay in business. And many, like Oyster, are giving up the fight. "The dealer can no longer be competitive,'' says Dennis DeCota, executive director of the California Service Station and Automotive Repair Association. "The companies are squeezing these guys out. It's just wrong.'' Oyster says his rent has gone up exponentially. Fifteen years ago it was $1,000 a month. Then it went to $6,000, then $8,000. This year Shell came back with a demand of $13,000. DeCota and Oyster see [a] sinister motive: If the dealers like them leave, a company like Shell can run its stations with its own employees and set its own pump prices. "That way they really are controlling it from the well head to the gas pump,'' says DeCota. While the price per gallon gets all the attention, Oyster says the little secret of independent dealers is that, like movie theater operators, they make their profit on the extras -- snacks, drinks and other items.