I think they are a few around but they are rarely for sale from what i have seen. I think i saw some selling for $200 a while back though.
I wouldnt consider them as mildly venomous either, most books i have read class them as potentially dangerous especially to young, old and immunocomprimised ppl.
If you want something that wont be a big deal if it does bite you i would go for a marsh/swamp snake, white crowned snake or one of those other little ones. I dont know how common they are though
Most of these snakes will often be feeding on lizards and may need to be weaned onto mice(if possible)
Green treesnakes have mild venom too they go for about $300-$500 as hatchies.
