Right now Walmart.com has these adorable First Act Disney Acoustic Guitars on sale for only $18.88 each, regularly $35! You get your choice of Disney Cinderella or Disney Cars Mater for ages 4 and up.
They also have the mini-guitars for only $12.88 and a few others to choose from. Perfect for your little aspiring musicians.
(For comparison, Amazon has these at $34 and up!)