T-Mobile just dropped word via a quick press release that the Samsung Galaxy S Relay 4G will be available nationwide at T-Mobile retail stores, select national retailers and online via T-Mobile.com beginning September 19th. Expected to cost $149.99 after a $50 mail-in rebate with a qualifying Classic voice and data plan, the Relay 4G will also be available with a qualifying Value plan for $99.99 down and 20 equal monthly payments of $20 per month.