Hi Cassie, thanks for the question. Bloggers, vloggers and 'influencers' are the celebs of today. The agency I work for, Viva PR, has won multiple awards based on the work we have done alongside influencers to help promote brands and change perceptions.
I think what's important to consider is whether the influencer is in line with your brand rather than just picking anyone. Do they share the same values / have the same taste / will they compliment your brand? If the answer is yes, then yes it's definitely worth approaching them. The payment can differ depending on their following. Some will do it just because they believe in the cause, others are happy with some freebies, and some want cold hard cash. I would recommend requesting seeing any content before it is published, and also agreeing the scope of work, frequency of content/images/videos/posts in advance so that both parties know what is expected of one another. To approach them, if you don't ask you don't get. Drop them a DM, send them a message, call their agent. Be brave. I hope this helps?