bet,
Just a thought: The mom could keep it a surprise by wrapping up a fancy oversized "cheque" made out to your grandson in the amount of 1 banjo. And then after the holiday hoopla she can take him around to stores to try different ones himself and have the staff play them too. He already plays a fretted instrument so I'm sure he'll quickly learn 2 or 3 chords from the staff to help him get a feel. They can talk to him about tunings and the different types of banjos as well. Definitely used banjos are a better deal. I like a store that serves local professionals. Good luck!! This'll be a great Christmas in Tucson one way or another :-)