I got my substrate at Petsmart and Ace Hardware. The Coconut Fiber was $8 for a gigantic bag and is resistant to bacteria and mold which is a big deal. I bought the vermiculite from Ace. I went with a 1:1 mix of Coconut Fiber and Vermiculite because of the water retention and ability to stay together for burrowing. I am using 4" deli cups you would get potato salad in and they will work until the slings are 1-1.5" according to what I've read. I can't help with specific species because I'm not that familiar with them yet. There are some great stickies on Arachnoboards though and Jeff and Alexa can lend some guidance if you get the time. I'm excited to check them out whenever I'm in the room! My big Seemani has made a few burrows which is amazing to see him in and out of. They are all eating great so far too. I'm totally glad I got these little guys
Regards,
B