Protection While Selling Instagram Account

So I currently have an account that just passed 30k followers. This was all done by myself over the past two years without any sort of bots or anything and someone is interested in purchasing this account from me.

They currently own an account in my niche with 150k followers and want to acquire mine for some reason. We have come to agree on a price of $8,000 (I know…) but I just can't help but fear that they'll do a charge back on Paypal.

Can anyone point me in the safest direction for…

Protection While Selling Instagram Account