Yes, I have seen any number of random plants (including non-Aloes) for sale as "Aloe vera". I guess that's a name that moves product.
The real thing is not at all rare, fortunately (and one of the most common garden plants around here, succulent or not). So if you go out looking for it, you will probably find it without too much effort or expense. I did spend quite a bit of time removing incorrectly identified images from that Aloe vera page, so you can be reasonably sure most of the remaining ones are the real thing.
My advice to anyone seeking a medicinal aloe for regular home use, especially topically for relief of skin problems, would be to spend 5-10 minutes looking at some pictures of Aloe vera, so you have some idea what distinguishes it from the great variety of succulent rosette plants that are in the ballpark. Usually the one your grandmother has is pretty good.
And do not eat any aloe that you cannot definitively identify as medicinal, since there are actually a few poisonous aloes (which fortunately are very uncommon in cultivation).