Has your son been a camp or showcase before? If not, this looks to be a good experience if the travel costs are low.
If he has, then I would look at the nature of the email sent. Was it meant to be a broadcast email or targeted at your son by one or more of the schools. Would your son be willing to reach out to the participating schools to learn more about the camp and also to introduce himself.
When my son was just starting out with his recruiting efforts he would attend larger showcases/camps to get a sense for what they are about, network, and just listen to what they have to say. Typically, these were local and not terribly expensive. His travel team would have showcase days and bring in multiple colleges to watch their practices and drills. It was good experience for him on how to showcase. Also, many of the schools that had him on their list could also see him pitch at the PG WWBA in East Cobb
As he got into junior year, it was much more targeted toward schools he knew he wanted to pursue. In his case high academic showcases camps. He felt he would stand out there, and he did. Interested schools were then asking to have him come to their prospect camp (end of summer) to have the all the coaches get eyes on him, tour the campus, etc... We learned this was a very important step. One coach can't recruit and offer a kid. Basically, the coaching staff has to agree with the HC having veto power.
So, I think you can look at this a couple different ways. If your son is interested in the schools on the list you might as well go because chances are good that if they are interested they will want to see him more than once. My son had a few offers across D1 and D3, and all of them saw him play/showcase at least 3 times. Two local D1 schools saw him play at least 6-7 times. Also, I know budget plays a large part in our lives, but there is a cost of doing "business" in college baseball recruiting. If you can get him quality exposure to his targeted schools (without an airplane ticket)....do it. I drove 8 hours to a school (one-way) because I knew he was going to get offered to one of his dream schools. My thought process at the time was that you only get one shot at college baseball recruiting....so we hopped in the car.
As always, JMO. Good luck!