I get the impression that there are a ton of parents and kids out there that do not have the skills and connections necessary to manage the process of recruitment well. Some do have many of the skills necessary and may have the necessary contacts (a really good travel coach may be all this is required). But, for those that do not have the complete skill set, a PG showcase - at the appropriate time - can prove invaluable in getting the kid seen by an appropriate audience and getting the necessary independent feedback to help get pointed in the right direction.
Showcasing alone won't suffice, but it can play a key role in identifying the appropriate pond, an exercise that is sometimes the most difficult of all. Maybe assume $1,000 all in cost with travel/lodging and start comparing that cost to other paths. If you fail to understand where the decision makers feel your son fits, you could spend many times that amount chasing a dream that will never become real. Conversely, if you can get that independent evaluation (tougher than it sounds) and then start getting in front of those schools in some capacity, you can skip the showcase altogether. I guess you need to understand the role the showcase can play in the recruitment program and then determine if that role can be met by another means - a presumably cheaper means.