National Rifle Association C.E.O. Wayne LaPierre used his opening speech at the N.R.A.s national convention today to highlight several challenges facing the organization, including what he called the rising cost of Senators. Over the past few years, weve seen the price of purchasing a Senator surge astronomically, he told the N.R.A. faithful. Unless something is done to make Senators more affordable, the ability of a tiny lobbying group to overrule the wishes of ninety per cent of the American people will be in jeopardy. The days are over, he said, when you could buy a Chuck Grassley (R-Iowa) for little more than pocket change. Now it costs thousands to purchase a marginally effective Senator like Kelly Ayotte (R-N.H.), he said. Mr. LaPierre was followed at the podium by the former Alaska governor Sarah Palin, the rock musician Ted Nugent, and several other people who would not pass background checks. 