The shrimp mountain is just some interesting craggy rock I bought from a store in St Louis. I don't know if it's lava rock or not.
I got my cardinal from phong on aquabid. I ordered some yellows from him (in my 5g tank) and convinced him to toss the cardinal in for me to try out, with the promise that I'll buy a group from him if I can keep the lone dude alive for a while. So far, so good. Phong was nice to deal with and packed very well, for what it's worth. But yeah, they're expensive. If I do get a bunch and they breed well for me, I'll ship you a few for $5 a piece (what I'll probably sell them for at my local store) + priority shipping, but it'll be a while
I think your water is fine, I'll post about that in the thread where you asked.