Amazon.ca: Amazon 2 for $3 items - Roomba part replacement kits

I recently got a used Roomba 600 series and it needed some replacement brushes etc - so I had a 32$ kit in my cart and when revisiting noticed it was part of a 2 for $3 promotion. I added a second different branded kit ($28, for a total of $62) and checked out and the total was just over $3 with prime free shipping. I don't know whether it requires prime but I activated it anyway. I also used a business account for the purchase though it doesn't mention whether this is biz account specific. Other items seem to be other robot vaccuum related replacement parts - the deal URL is to the list of items that qualify for the deal. These might all be irrelevant to you, but it was the most weirdly specific thing that applied to exactly something I needed and didn't want to spend money on that I had to post. Terms say it expires Oct 12 but also says it could be ended any time.