You can do what I did with my first ukulele purchase (from MGM.) Sign up for eBay, then sign up for PayPal and Live.com. Make sure all 3 accounts are linked.
Go to live.com and search for "ukulele." The first three links should be sponsored links. Click on the eBay one, it should say "Up to 25% off on qualifying purchases."
Buy your uke from MGM or any other store and after 60 days, they'll credit your PayPal 25% of the purchase price (not including shipping.) When you click BIN it make sure the next page says it qualifies for the cashback.
The % discount only qualifies if you use PayPal to pay for item and is only valid on "Buy It Now" items.
HTH,
Tam