As much as we really like and even seriously appreciate the design work that goes into OtterBox's higher-end cases, its cheaper Impact Series Case for iPhone 4 ($20) isn't quite as impressive -- Impact borrows some of Commuter and Defender's design touches while sacrificing protection and really shaving down the price. On a positive note, the case has really grippy sides, Home Button coverage, and covers for the Sleep/Wake and volume buttons,…
