Carphone Warehouse and O2 have run out of 8GB iPhones after cutting the price by £100 to £169.
Both companies have reported selling out at the discounted price, although Apple still has units available for those willing to pay the full price.
Retailers in Germany and the UK are trying to shift stock as fast as possible before the expected release of the 3G iPhone in June.
The lack of 3G was seen as a major flaw in the iPhone and analysts have been predicting a new version for months.
The new iPhone is expected to be slightly thicker than previous models because it is rumoured to have GPS integrated in addition to 3G.