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A lot of it is features such as construction, included software, a cool look, etc., but there are also real differences. I've used a USB drive that I got as a freebie at a trade show that worked ok on a Windows machine, but was not recognized by my Linux desktop, for example. Beyond features, which along with capacity drives most of the cost, there are very real differences in speed between some USB drives. Many of them are fairly close in performance, to the point that you wouldn't be likely to notice the difference in normal use, but some have much sloooooooower read/write speeds, and with large files that does make a difference. San Disk is a good product, usually at the high end of speed benchmarks, even if not always the absolute fastest, and they have a lifetime warranty, so you do get what you pay for. San Disk has also been a Ducati Moto GP sponsor, and makes Ducati edition products, so they get big bonus points from me for matching my racebike!