Yep usually straight from the LFS. Its something that can grow quite rapidly so I'm sure they will have some on hand almost all the time. For a beginner I definitely recommend it over caulerpa, which can actually turn out worse than better for someone who is inexperienced because it is a potent and noxious algae. So I'd say that chaetomorpha is probably the way to go for now.
I myself haven't gotten anything from them yet but I am placing my order on Friday. All I've heard is amazing things about them. I myself have 7 Red mangroves in my Refugium and after I place my order, I will also have Cheato and Ulva as well. Hope this helps!