CaliforniaMMO via Amazon offers the Samsung 512GB 830 Series SATA 6Gb/s 2.5" SSD, model no. MZ-7PC512B/WW, for $498.98 with free shipping. That's the lowest total price we could find by $301.

Update: The price has increased to $499.98. Despite the increase, it's still a price low (now by $300).