(Reuters) - Online used car seller Vroom Inc said its initial public offering was set to be priced in the range of $15 to $17 per share, aiming to raise about $318.8 million at the top end of the range. The company is offering about 18.8 million shares in the IPO and is expected to have a market capitalization of $1.92 billion (1.5 billion pounds) at the higher end.