The last few times down to Cuba there are certain items that we find you cannot buy at resorts but if the resort had them many would be interested in purchasing them.
Sweat shirts - either because when you get there it is unexpectedly cool or you want one with Cuba on it for home
Insulated mugs - for drinks
At some resorts we have also not seen (but have at others) but all should sell....
Sunglasses (Breezes Jibacoa doesn't sell them but next door thank goodness did)
Pool air mattresses
Anything that anyone else can think of that really should be available at the resorts and that you would most likely purchase.