Thanks to all for the input.
The oldest (7) decided he wanted a Stratocaster after seeing a picture of George and John with their matching Sonic Blue guitars. His grandmother bought him a Squier Affinity Strat. The youngest has decided he is saving money for a drum set while learning to play the piano for now. He came close to buying an Epiphone Viola Bass, but decided that the order he wants to learn instruments in is piano, drums, guitar, bass. For a 6 year old, he's pretty discilined with his money.
It is all thanks to this game, playing TBRB really got them interested in music. It's all the youngest wants to talk about, while the oldest goes to sleep everynight listening to Beatles albums on his CD player.