My name is Ian and I live in Perth Western Australia. I bought a Pi-Top laptop from www.pi-top.com
for my Raspberry Pi 2. It cost me $400 AUD delivered (May 2015) without the Pi computer module, so it's quite expensive. The Pi-Top laptop comes as a kit which you assemble; for me that was a clincher. Included in the kit is a 13.3 inch integrated LCD screen, chicklet style keyboard (you can elect for UK or US style when ordering), power supply and all screws, nut, cables, etc to build you own Raspberry Pi laptop. The battery has caused some issues, especially it let fall below 15-20% charge. There is an active on-line forum and heaps of support from other users. I've since uipgrade my Pi-Top laptop with an RPi-3 - a simple bolt-in replacement.
Pi-Top are also almost ready to deliver a cheaper screen version which uses the same screen, power supply and cables called the CEED for $99 US plus delivery. This is not a portable device, but a desktop device.
Take a look and see if it may suit your son. It looks like it provides a nice 14 inch screen and housing for the Pi, and includes a power supply and expansion bus for later developments. There is also a speaker which can be purchased and added for, from memory around $20 US plus delivery.
I've also seen a neat kit called the Kano Computer Kit for around $150 AUD that comes with an RPi 2, wireless keyboard and mouse, speaker, custom case with cables and power supply, 8GB SD Card with KanoOS and books to get started. This like the CEED looks to be good value.
Hope this provides some info for you. My feeling is that the Raspberry Pi is a great product, similar to the likes of the old BBC micro, Sinclair Spectrum and Commodore 64 computers of the 1980's, only more accessable and with a much cheaper investment. Good Buy!