Hi Crapmemory, I'm was a Level 2 Fitness Instructor, but after 4 years of working in the industry, I have just completed my Level 3 Personal Training Certificate.
Most local colleges run Level 2 courses mine was done through the YMCA and because at the time, I wasn't working the course, which ran for 8 weeks cost about �36.
Buy a Floodight course book and see what courses are available in your area. If you do them privately through a company like Premier or even the YMCA, you are looking at paying over �1000.
If your son want's to work in the Fitness Industry as an instructor, then he mus have a minimum of Level 2. A trainer cannot instruct unless they are alsoregistered with REPS (The Register of Exercise Professionals)