A couple things to think about...
One thing I have never liked about what we do is the cost associated with attending events. It is too expensive! However, in our case it has to be that expensive. If we did it part time, worked out of our house, and found a field, and our job was over when the event ended, we would make a fortune. Instead we have a building, offices, an extremely large pay roll for about 60 full time employes and hundreds of seasonal/part time workers. After most events we have people working for weeks compiling information and filing reports from that event. I'm not complaining, just trying to somewhat justify the cost involved. Our profit margin is much smaller than others who do the same thing. We might spend more money than all the others combined.
That doesn't solve the problem, though. We understand there are many who simply can't afford some of the things we do. After all, the cost of the event isn't even the most expensive part. It costs much more in travel, lodging and meals unless the event is in your area of the country. We try to help as much as possible when we know of a talented player that can't afford these things. It is difficult because of certain NCAA rules. We really don't have that much to offer to the kids that lack talent, so they are better off saving their money. The way we have helped many is by getting other baseball people to help them, we have lots of contacts. People who can help them without worrying about NCAA rules. Sometimes it is their team or a team we know will pick them up. After all, lots of people are interested in helping talented baseball players. There are programs out there that work with kids that are under privileged. We try to work with several of those programs. MLB tries to help those kids also, especially in the inner cities. Our job is to find talented players, whether they come from wealthy families or from poverty makes no difference. We have helped many poverty stricken kids, including some who are now wealthy Major Leaguers.
Often there is a discussion about size on this site. Size is important but talent is much more important. Same could be said about this topic. Money is important, but talent is much more important. I think if you check the history involving PG, you will find a very large number of current MLB players. Surely no one thinks these were all a bunch of sons of rich people.
I will say this, if someone only throws 30 pitches at a PG showcase, they have probably thrown very well. The average appearance is more like 50 pitches. It really doesn't matter, though, other than endurance why would anyone need more than 30 pitches to show their ability? Sometimes it takes no more than a few pitches to know what a pitcher is capable of. You could throw 200 pitches that interest nobody or you could throw 3 pitches and have everyone interested.
Back to the original poster... Based on what you have posted, I think the best approach would be to find the colleges that fit your goals. Chances are, based on what you have stated, you might be best off looking at smaller high academic colleges. Because your son has a strong desire to play baseball, I would visit a couple of those colleges during the season and watch a couple games. Get a feel for the talent level you are watching. Try to determine how your son compares.
Anything and everything is possible, but chances of being happy are best if your in the right place. 78 mph pitchers really need to be seen. Nobody is going to get excited when they hear 78 mph. That simply describes a pitcher that could be anywhere from very good to very bad. My honest opinion is to forget about any individual showcases. Try to get on a team that plays at events that college coaches attend. Go visit colleges that interest you and might want you. I will say that the 6'2/150 LHP peaking low 80s with good control and three pitches should create some serious interest. Possibly even at a DI college, but for sure at some smaller high academic colleges. Unless he is exceptionally good, I agree, I doubt if spending $600 at a PG showcase would be a good investment.
I've said this a thousand times. Please understand! We don't want your money unless you have some talent. If you have talent, you're likely to be very happy you spent the money. If you lack talent, you're probably throwing your money out the window. There is very little anyone can do for you unless you have talent. If you're not a good player on your high school team, why spend money trying to impress people who see the top players in the entire country. For some reason I think some people think if they spend the money they are buying into the future. It just doesn't work that way! Remember... Talent is much more important than money in the end.
I know that PG has a good reputation as one of the best when it comes to showcases and tournaments. If you have a son and he is not a "good" HS player I would rather you give your money to some other showcase. You won't have any problem finding some that will want you.