For discount shops
Is your shop focused on selling highly discounted products? Then using a normal generic domain name will only be hurting your business. A .CHEAP
domain on the other hand will put it out their straight away that your shop is offering the cheapest deals on products, that way you will spend less on ads.
For used products listing pages
Used products are naturally cheaper than it new version. So using a .CHEAP domain for your used product listing website will fit perfectly and also help
you to gain more publicity.
For limited discount page
Have you ever tried to leave a sales page of a product and then your get a pop up displaying a much cheaper price than earlier? Or you get a link in your
mail leading to a slashed price for a product you are interested in, but the discount is more a limited amount of time. This is a perfect method of making
every visit to your sales page count. Using a .CHEAP ending for your discount page will help to separate your actual sales page from the discount page.
Some people are cool with the original price while for some it is just to expensive. That way you can easily serve both set of people.