Under $100 is a difficult one. Its hard to find a bow for an adult that will have the proper fit and not need work, let alone a kid who is still growing, for under $100. If you decide to spend more than $100 dollars I would highly recommend a Diamond Razor Edge package. The next time your son will need a bow he should be on his own and out of the house. The draw length adjusts from like 25" to 30" and draw weight is 40# - 60# adjustable. Its a good setup has the sights, rest, and quiver. I bought one for my wife a year ago she was shooting the Micro Midas it just wasn't cutting it for her so we got the Razor Edge. Bow is fast, quiet, and light. I've shot it up against the Trykon I used to have and actually found for the money the Razor Edge costs I'd take the Razor Edge over a Trykon. The complete package should sell for about $349-$379.