While I like your idea, I just want to give you a few ideas before you reach that point.
Whenever you post a reptile on Craigslist, Facebook, or any other social media site and it says "free", you're going to be attracting a pretty unique crowd. That is not to say you won't find appropriate homes for your snakes, there ARE good keepers out there who will take them. However, whenever I find myself posting something for "free" on Craigslist related to reptiles or not, I often find myself wishing that I hadn't ....simply because the amount of jags (can I say that?) you run into are not worth it.
I would personally advertise the ever-living crap out of them on Morphmarket, Facebook communities, and other social media sources with a small rehoming fee. Normals I would charge $40 (personal preference). When you require people to pony up some $$$ you usually eliminate most of the jokers right away. You might have them a bit longer than you'd like but don't worry, you will find good homes if that is your main concern.
I just think you would find better homes by asking for a small rehoming fee.
OR.....
You could post an ad here and offer them for free to users you trust in exchange for the shipping costs. It's pretty easy to see who is trustworthy on this site.
My $0.02 at least.