Meet olloclip Studio for iPhone: a protective case with an integrated rail mounting solution that lets you use your smartphone to capture photos and video like a pro. You get a two-finger grip for stable videos. There are also 1/4-20 clips for a tripod or handles. Want to attach a microphone or light? There are cold-shoe adapters for that.
This particular kit comes with 3 lenses in 7x, 14x and 21x magnifications for a combined over 80x magnification. Sets you back under $150.