Over at Walmart, you'll be able to head to stores starting at 12:01am local time, according to a spokesperson. If you don't want to go to the store in the middle of the night, you can also order it online beginning at 10am PST. The representative did not discuss how many units are expected to be available when the NES Classic goes on sale.
Target will also carry the NES Classic. A spokesperson tells Thrillist that the console will only be available in store. "We anticipate demand for the item will be high," the spokesperson said, "and we will be replenishing inventory through the fall."
Other stores that initially carried the NES Classic when it was first released have not responded to inquiries about whether or not it will be stocked on June 29. However, it's likely you'll be able to track down the system from other large retailers like Amazon.