Hi Jsmith,
I buy sites for PBN's but as yet not into selling any... I look at the authority metrics of a site - so its helpful when that data is provided such as number of backlinks (together with Moz DA, Majestic CF/TF etc)... For buying/selling also consider Sedo, Godaddy auctions as well as digital point being good alternatives...
In addition if you sell your site with the content on it - you'll get more money! Even if is a relatively new site - as long as its unique content you can attract buyers whom are looking for an out-of-box solution as that tends to be much cheaper than writing/developing new content... So mention whether the content is included....
Also provide traffic and ranking stats if you can.... as that definitely helps...
Good Luck with it!
Cheers,
Sid