Part of the marketing done by a number of showcases are to get the various coaches who will be attending the event to email their lists, or the showcase list, a "personal" email. Essentially they say something like "I will be at so and so showcase and have heard that you might fit our program, or I have seen you play" or something similar.
That is not to say that a particular showcase is not worthwhile, but in most cases they are marketing emails.
I had my son do this and suggest you call up and talk to the coach or the recruiting coach about the event. A great question to always ask is “where am I on your recruiting list? Am I number 1, or number 10, or 100?” Be specific and ask them what positions they are recruiting for.
This will help you in determining if it is worth your time and $$ for any particular event.