I've been searching for a half-terrabyte USB SSD ever since I missed the 480GB PNY walmart deal (I never, and I mean never, score on YMMV walmart deals, but like a sucker, I still try) Anyway...
Here's a pretty good deal: I'm seeing a $15 coupon "Save an extra $15 when you apply this coupon." on the Amazon page..
That brings a $69.99 price down by $15 to just $54.99
Has 32 reviews at this time (getting 4.8/5), and fakespot gives it an A
There are a few other coupons available, including a $129.99 minus $20 coupon for a 1TB ruggedized NAND drive at their amazon storefront: