I purchased a copy of NIS 2011 for $19.99, last year, thinking it was 1 User (3 PC) but turned out it was only 1 User (1 PC). Fortunately, the order was transacted through Amazon, and because it was purchased via 'fulfilled vendor' Amazon corrected the error. The originating vendor merely remarked that it was a simple error of listing in wrong item slot but they would only give me credit for a future purchase from their store. I ended up purchasing from Amazon, direct, for $29.99.
I'm not disparaging "any" of the offers in this thread but, nevertheless, it's something to be aware off.
Thanks for all the information.