This is how I initially got started with programming. We were required to purchase on of the TI-8X models of calculators for my high school math class. They come with a builtin BASIC language for programming. The language is simple and you can either use menus to add statements or type them. If you brother turns out to be really into programming he also can do as far as writing assembly language programs. In the more advanced models they have simplistic GUI elements for building windows, dropdowns and the like. It is a nice way to spruce up your program with little hassle.
In addition to the programming language you have the benefit of access to the mathematics capabilities of the calculator. Everything from statistics, equations, This is very handy when you want to solve an equation in a program but may not be ready to write your own subroutine to do that. They have limited graphics capabilites, only grey-scale graphics and no sound. I think that as a first excursion into games and programming those items are fun but not required. Lastly I believe one of the strongest reasons to get something like this would be that it is portable. No need to bring a laptop, inverter, etc... I spent many hours in the back of my parents car typing away on my calculator. Porting games or even utilities for my math and physics classes. It was about either having fun or solving a problem that was important to me.
My personal favorite is the TI-Voyage 200. It has a qwerty keyboard, larger screen and does symbolic math. Chances are if you brother is going to take a math class beyond Geometry he will probably want to have one of these anyway.
Best of Luck!