Looking at various and sundry tile shops, I found a good decorating to cost compromise at Home Depot. Real slate for the floor, belt line, and edging but ceramic "slate-look" tiles for the walls. Here is the mosaic that will go on the stall floor and decorative spots (I've provided a link but have no idea if it'll actually work - still learning this blogger stuff!):
The 1"x2" size is great for getting a good grip on the shower floor and since this shower won't be used that much I'm willing to take on the extra work of re-sealing the stone occasionally. I actually considered using real stone from the property but was concerned it would be sharp on bare toes. This has been tumbled to round the edges a bit and should be more comfortable to stand on.
The ceramic tiles for the walls have a slate look. Unfortunately this photo looks more brown than the grey color it is in real life (which is why I have such a hard time buying decorating items off the internet; colors just don't show true depending on your screen).
A black semi-transparent stain on the wood cabinetry is planned and the fixtures will be white. I think it's going to come together great.