Not every job needs a barge and a crew. Four concrete mixers and five plate compactors go out for a single day at a time, with no operator and no licence needed.
If you are already hiring an excavator, these travel on the same barge and add nothing at all to the freight, which is worth knowing before you buy a mixer for one slab.
A spare drive belt goes with every mixer, because that is the part that fails and it fails on a Friday.