One of the best deals on wireless headphones during Prime Day earlier this month is back. The Beats Solo 4 headphones, which only launched in April, are 50 percent off at $99.99 ($100 off) from Amazon, Best Buy, and Target, matching their all-time low. If you prefer over-ear headphones or need active noise cancellation, the Beats Studio Pro fit the bill and are also matching their record low price of $169.99 ($180 off) at Amazon...