Our faculty require new students to purchase a kit from Mehron. The kit has brushes, cream sticks, highlights and shadows, and retails for less than $50. I'd give you the URL, but that's against the cc.com rules. However, if you'll do a search on the term "Mehron", you'll find their website. Follow the link to "Educational Theater" and from there to "makeup kits". We've never had a problem with this makeup.
I notice that they offer a different and slightly more expensive line that is advertised as being appropriate for sensitive skin. I can't make a recommendation about it. I suggest writing to the company or calling them and speaking to a representative about your son's particular condition.
As be_a_star mentioned, Ben Nye also manufactures makeup for actors. I haven't used their products recently, but they are a reputable company and worth checking out.
Hope this helps.