Amazon is featuring a deal of the day on SK hynix Gold S31 3D NAND 2.5 inch SATA III Internal SSDs. You can save up to 20% on these up-to 560 MB/s SSDs, today only (or until sold out).
The 500GB drive is $45.59 and the 1TB drive is $83.19. These items are sold by the manufacturer (SK hynix) via the Amazon marketplace, but shipped by Amazon.