Based on some reliable sources, Engadget is reporting that Best Buy will be offering the next-generation iPhone at launch which is June 24th. But the stores are expected to carry only 45 units of iPhone 4 - 30 for the higher-capacity 32GB model and 15 of the 16GB units.

Also RadioShack has reported on its Twitter account that it will be offering the iPhone 4 at launch too and that it will begin accepting pre-orders with a $50 deposit on June 15 which is the same day that Apple would also be accepting iPhone 4 pre-orders.

Not only that, RadioShack will also be accepting trade-ins for the iPhone 4. It will be reportedly offering as much as $100 credit for iPhone 3G units and $200 for iPhone 3GS units. You can get more information on the company’s trade-in program website. However, there is no information on how many iPhone 4 units it would have for sale.

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