Yes, Aliexpress is legit. I've purchased quite a few things from Aliexpress before. Essentially it's like an Ebay except these are merchants who buy stuff in bulk from factories then resell it at a slight markup. Thanks to the Chinese government subsidizing much of this, the online retailers on Aliexpress can offer stuff like USB Type C cables for $1-2. There are a couple shady merchants on there just like on Ebay or Amazon, but generally speaking I think you'll be OK. The only big downside to Aliexpress is that their stuff will likely ship from China. As a result, you'll probably need to wait several weeks to over a month to receive your item. In my experience it takes about 3 weeks to go from China to the west coast of the US so if you live farther inland I imagine it'll take even longer.