There are two options here.
1) tech can replace the neck receiver (generic ones available via supply outlets). This may or may not get quasi-costly, depending on whether there are any mounting posts ON the receiver, like for the octave key or not. If not, probably a $50-70 job. If so, maybe $75-100 job.
2) cheaper solution: tech can simply soft-solder on a patch (brass sheet metal) over the crack...much the way we see neck patches on damaged necks. It will arrest further cracking and it will make the receiver function fine again. The patch will be visible, of course, if that matters to you.
Perhaps a $30-50 repair.