Most cruisers use other cruisers as line handlers. If you go through first as a line handler on another cruiser's
boat you will understand the process and have a more enjoyable transit on your own boat.
Hiring line handlers does not necessarily mean you get qualified people. There can be langauge issues, there can be ego issues and there can be incompetence. I've seen paid line handlers going through on their very first transit.
It is easy to rent lines on either end of the
Canal. It is also easy to arrange your transit without using an agent.