Selling Environmental Blog Network PR6, 6 years old

I'm looking to sell my blog network, I'm not sure what's the best approach for selling it... weather it be here or flippa or if I should somewhere else... anyone have any advice?

Here is a description:

This is a sale of the entire AboutMyPlanet.com blog network. The network includes 5 websites, AboutMyPlanet.com, HybridMile.com, EcoFriendlyDaily.com, GirlSustainable.com, GadgetAddiction.com, and GrowNews.com.
The reason for the sale is that I don't have the time to run the sites any longer, they're on auto pilot at this time, the authors publish content and you collect the money. A few years back the sites were generating close to $10,000/m this was before the big financial crash. At this point the sites generate $500-$1000 a month.
The main site, AboutMyPlanet.com is a PR6 site. The other sites are:

• EcoFriendlyDaily.com - PR4
• HybridMile.com - PR5
• GirlSustainable.com - PR2
• GrowNews.com - PR3
• GadgetAddiction.com - PR1

I believe if you have the right skills, you can make quite a bit of money on the affiliate side of things, we had a few months just as the big financial crash was happening where the sites were bringing in $1000s in affiliate sales.
The sites over the 6 years have generated over 3.7 million visits.
The network owns all it's content, every single article has been written directly for the network by original authors. The entire network original content library is over 7700 original articles.