Virgin Mobile's 20 percent off promotion is good only for August 27, 2013. Prepaid customers can get a 16GB iPhone 5, regularly priced at $550, for $439. The 32GB model, normally priced at $650, sells for $519, and the typically $750 64GB model sells for $599.
Virgin is also offering the 8GB iPhone 4 for $280 and the 16GB iPhone 4S for $360. Visitors heading to Virgin's site for the promotion will find the devices listed at their normal prices, but the discounted rates will become visible upon adding them to a cart.
The next generation of iPhone will likely be introduced at a media event scheduled for September 10. That event is expected to mark the debut of a new low-cost iPhone model as well, one that may be better targeted at consumers using prepaid carriers such as Virgin.