Question about selling my MFA Sites

I have several wordpress sites made for adsense all on the same niche and most are making over 600$/month and want to start making more and selling them after a couple months. I provide the targeted traffic and can continue to do so after the site is sold. What should info should I include when selling sites on flippa and how much would a simple WP site making 600$+/month go for?

Over $6,000 per website, if they're really earning $600/per month anyway.

Well I have a couple making 800$/month, non of the sites a ranked good and 95% of the traffic is from my unique source. Does this make a big difference to people buying sites?

$10K is a very reasonable price