Marketers can reap big payoffs by tapping social media influencers, of course. But using them isn't cheap. Brands can expect to pay influencers $1,000 per 100,000 followers on Instagram and upwards of $200,000 for a celebrity who has more than 100 million followers. Plus, the field is noisy and cluttered: Social media platforms like Instagram are teeming with both bigger and lesser-known celebrities paid by brands to promote products. That's why an increasing number of marketers are turning to nano influencers, or nanos for short.