The online solutions are clumsy and will not drive additional sales since the sale prices are not visible on the product pages. Anyone who does online retail knows you need a visual callout of the reduced price on the product page. This is pretty basic functionality, and given that we pay Shopify $2,000 a month I strongly feel that this feature (the ability to put a collection on sale) should be included with Shopify Plus without the need for yet another add-on app.