Question for Creative Business Individuals.

Hey Warriors,
I need some ideas / insight.
I have a large network of sites. (main domain + 50+ subdomains.)

Each one of the sub domains have been created by hand. Plus marketing campaigns run, and monetized. Each one of them earns $1-6 per day using adsense.
I plan on adding ebay and amazon soon enough.

Anyhow, I am thinking of selling the sites off. However, I do not want to just sell off the entire site. I would rather sell off each subdomain either through flippa, or perhaps even rent out each site.

The subdomains that I have now need regular updates, and some weekly marketing. Running all 50+ of them is a part time job.

If I split up the sites and sell them off, do I get seperate domains, and route the original sundomain to the new domain?

Do you think someone would be willing to purchase a subdomain?

I'm not sure how to go about this honestly. I have even thought of renting the sites out, and only requiring a few weekly updates and weekly marketing and perhaps giving a percentage of the monthly profit.
If I decided to do something along these lines, how would I establish it?

I have thought of simply hiring freelancers to keep up the updates, but Im afraid of how time consuming it would be to keep on top of freelancers.

Any ideas will be helpful.