The vast majority of deals are doen either via PM and email. The prospective buyer will post a note here in the thread to say they are interested and then the 'negotiations' are done privately. You might consider posting your Ebay name to allow some feedback checking since you are new here and you can check the FB of people on this site as well before commiting to a deal.
Just click on the buyers name and go to 'public profile' Then click on 'statistics'. Scroll down to find the forum feedback for that person. For example you'll find a page like this for mine:
https://www.pentaxforums.com/forums/feedback.php?u=2071
I'm interested myself (1000mm) and will wait till the pictures. If you are OK with it, our Lens Database is missing the picture from the 1000mm. If you don't mind I'll send one of your pictures to Adam for that.