Consumers already spend more than half of their time interacting with online retailers from a mobile device. And as that number continues to grow, shopping enthusiasts are turning to price comparison apps to find the best deals. The price comparison app marketplace is a crowded one, but shoppers shouldn’t get the idea that all of them are basically the same. A comparison of two of these apps — ShopSavvy and RedLaser, eBay’s product-finder app — prove that’s not the case. …