The average cost per engagement (CPE) for influencer marketing varies based on the platform, the number of followers, and the category (or niche) you're posting about. 

Micro-Influencers typically have the highest amount of online engagement:

            Followers             Avg Engagement

Nano (1-10k)	5.71%
Micro (10-100k)	8.28%
Mid/Macro/Mega (100k+)	1.84%

According to Tribe, these are the average CPE by category:

Animal:                                                   $0.51
Beauty & Personal Care:                        $0.57
Entertainment & Events:                         $0.59
Fashion:                                                  $0.50
Food & Drink:                                          $0.57
Health, Fitness, & Sport:                         $0.49
Home & Garden:                                     $0.54
Photography, Art, & Design:                    $0.49
Social Enterprise & Not-For-Profit:          $0.38
Social Media, Web, & Tech:                     $0.45
Travel & Destination:                               $0.51