This set just keep going down in price! Amazon America now has LEGO Disney Princess Ariel’s Undersea Palace for $39.17 (reg.$54.99). Savings now work out to be 29% off. LEGO Star Wars General Grievous Chase is also down to $19.99 (reg.$24.99) which works out to be 20% off.
Thanks to forum member TheKragle for the tip.