Best Buy offers the Samsung 850 Pro Series 128GB Serial ATA 6Gbps III 2.5" Internal Solid State Drive, model no. MZ-7KE128BW, for $89.99 with free shipping. (Amazon charges the same.) That's the lowest total price we could find by $5, although we saw it for a buck less in December. It features read speeds of up to 550MB/s and write speeds of up to 470MB/s.

Update: The price has increased at Best Buy; however, Amazon still offers it for $89.99 with free shipping.