Will's mommy, don't know if I'm too late.  you can save money on laminate by shopping around and even ooking online but you don't want truly cheap laminate, it's going to be tougher to put together and may not last as well.

A few suggestions:  glueless-lock together styles are easy to install and don't outgas anything that would be harmful to your son's system, glues can.  

Replace flooring in his bedroom first!

We put in Alloc flooring for similar reasons and we found it very durable, I don't know the other brands.