I sleep under your bed
This is exactly why you should install the stuff you like in your house and not worry whether or not the next owner might like it. We tore out the nicest carpet we've ever lived with when we bought this house and replaced it with tile. I suspect the next owner will carpet over our tile. We ripped out the gd rosemary bushes that a previous owner (a landscape architect, no less) planted and replaced it with native plants. The next owner will probably blade the yard and park trucks all over it. Trying to guess what will please a mythical buyer is a waste of time and money. Go with what you like.
For practical purposes there is no different. Unless the more expensive tiles clay bodies are design with stable low shrinkage clay and the cheap ones aren't, then there will be a slight different in tile uniformity in the cheap tiles. The more costly tiles could be porcelain or highfire stoneware thus making it stronger than terracotta or lowfire clay body tile, however there is virtually no different once the tiles are installed. It could be that the expensive tiles are made in more expensive area, or aren't selling as well as the cheaper ones, therefore the price are higher.
If you want to add something natural to the look try a pebble wall where the green tile is placed now (wall only)
Something like this:
Would add a great accent to the room.
No more than other tiles. A couple coats of sealants on the grout, and anti slip wax would keeps the grout clean for many years.
