Since you already have transmitters, might be better to not get a RTF. Do you already have a charger that can do lipos and/or extra lipos? Here are some other ideas where you could use some of your radios:

http://www.amainhobbies.com/product_...rce=google_ext

http://www.redrockethobbies.com/E_Fl..._p/efl2900.htm

http://www3.towerhobbies.com/cgi-bin...?&I=LXXJS4&P=0

Even more options open up if you're open to a kit. StevensAero Squirt400, Mountain Models Dandy, GWS E-starter, just to name a few all would be good choices. Plus might make it sort of cool for him to help build and get to choose the colors to make it unique to him. With any of these you could just get some inexpensive ESC/motor/servo combos from HeadsUp R/C or Hobby City.