Jet.com offers the Mushkin Enhanced Reactor 512GB Serial ATA 2.5" SSD, model no. MKNSSDRE512GB-XT, for $128.85 with free shipping. That's $11 under our mention from last March and the lowest total price we've seen. (It's the best deal now by $16.) It features read speeds of 560MB/s and write speeds of 460MB/s.
Note: You can also receive additional discounts during checkout by waiving free returns or by choosing select payment options.