Update: Radio Shack announced the promotion in its weekly ad on Sunday. The ad notes that the $30 off sale for the 16GB iPhone 4 is valid from July 31 through August 6.
Tipsters sent Engadget a leaked photo (below) of what appears to be an internal document for retailer Radio Shack. According to the leak, the new prices, which require a new or upgraded 2 year contract, will take effect on Sunday, July 31.
Early 2-year upgrade customers can purchase the 16GB iPhone 4 for $399.99 and the 32GB model for $499.99. For customers looking to purchase the device without a contract, Radio Shack offers the two models for $749.99 and $849.99.
Meanwhile, a separate rumor claims Target will drop the price of both the 16GB AT&T and Verizon iPhone 4 models to $149.99, also on Sunday. An anonymous tipster told Phone Arena that the 32GB Verizon iPhone 4 will sell for $249.99, while the retailer will continue to sell the 32GB AT&T version for $299.99.
Target is also said to be offering up to a $100 off a new iPhone 4 with a trade-in promotion for the iPhone 4. Unlike the Radio Shack leak, however, the tipster was unable to provide evidence of the upcoming promotion, leaving the report unverified.
Last December, Radio Shack offered an aggressive sale of all its iPhone handsets with a temporary $50 price cut along with trade-in incentives. That sale quickly left the retail chain with a shortage of Apple's smartphone.
Discounts on the iPhone 4 could become increasingly common as Apple's release of the next-generation iPhone nears, especially given the fact that the handset is now over a year old. Numerous reports have suggested that the new device will arrive in mid- to late-September.
Apple has traditionally continued to sell the previous year's model at a discount. A set of photos released earlier this week claimed to show that Apple is working on a lighter, cheaper iPhone 4 revision that could be introduced alongside the so-called iPhone 5.
The next iPhone is believed to be thinner and lighter and include the A5 processor and an 8-megapixel camera.