A German economist has filed a lawsuit against OPEC with a Berlin court, accusing the cartel of pushing up the prices of the gasoline and heating oil he is buying, Bloomberg Opinion columnist Javier Blas reports—and despite the paltry sum, the suit could end up costing OPEC more than it can afford. Armin Steinbach, Professor of law and economics, is suing OPEC for damages for $50 (50 euros), plus interest, alleging that OPEC is an illegal cartel operating to drive up oil prices. The court has allowed the case, which is a rare legal challenge…