How to safely sell instagram account?

Hello. I’m not trying to sell my account here. I have an instagram account in tattoo niche which has over 365.000 followers, in order from biggest to smallest, from countries like Brazil, USA, Mexico, Argentina, Italy and so on. The other day some guy messaged me on instagram asking me if I interested in selling and offered me 1800$. I didn’t say yes for now. So how to make sure that he won’t scam me? And also that price is low or it good for my kind of account?