What would be a cheap tile adhesive for an undemanding application, to new
dried plaster, normal light ceramic tiles in a bathroom/shower location?

Unlike the floors, I don't need anything fancy - but now I've plowed through
all the fancy products, I'm somewhat lost now I need something normal...

Using Mapei for everything else, but this doesn't have to be one of theirs.
All I know is I'm happy to mix from powder as it's probably better and I'm
not bothered about vertical slip properties as I'll be using tile spacers.

Ta

Tim