Right before MPA-3c’s release, Monster Cable contacted us with an unusual pitch: what if you could get more features, cheaper and sooner? The “more features” and “sooner” parts didn’t happen—we only saw the company’s iSoniTalk ($20) in stores late in 2007—but at half the price, there’s no doubt that it’s a better deal than the MPA-3c, and surprisingly comparable in performance. Just…