If you want to grab a Galaxy S8 or S8+ from a US carrier, we've already told you what to expect in terms of pricing and release dates. But what if you want to buy unlocked? Best Buy has thankfully been nice enough to answer that question. The retailer has revealed both the pricing and the release date for the S8 and S8+ unlocked units. These will be available on May 9, a fair bit after their carrier-specific counterparts launch (starting on April 21). The unlocked Galaxy S8 will be priced at $724.99, while the S8+ will cost $824.99. That means you're saving $25 when buying unlocked...
Source: http://www.gsmarena.com/unlocked_galaxy_s8_and_s8_arrive_on_may_9_in_the_us-news-24272.php