Camps are good, as you noted, for technique. There are actually a few intensive - conditioning/mental toughness - camps out there, but that being said, if you are trying to compete on a high level, getting in shape in June/July/August isn't going to help you much in February's state tournament.
Now certainly you can learn conditioning practices, theories, and learn new ways to better prepare, but to pay someone for that in my opinion is a bit silly. There is a ton of litterature out there about high level conditioning and core strength as it applies to combat etc. I would pay for the high level technique, that's not always somthing you can provide as a father.
I would research and study the conditioning and help my kids on my own - that much you can do. In addition it's worth noting that most high level conditioning is very nutrition centered which plays a role in wrestling quite well. This needs to become more of a lifestyle - not somthing you pick up over the summer.