For many working people (myself included) the end of the month is the absolute worst time for a sale like this. We pay our various bills, and by the end of the month, the average working man (or woman) is for all ways and means broke. Doing this as you do is potentially costing you an enormous amount of revenue, and even worse, pushing the feelings of your community towards negativity, which is a potential death sentence.
Have your sales at the FIRST of a month, by the 5th. This will allow us to put this purchase in the budget, which I can almost guarantee will increase sales, and revenue.