Maybe the deal has changed since Flibb bought his.
I must admit that the way I read that advert, I assumed it would be dell toners not compatibles, and if I'd ordered and compatibles arrived, I'd have sent the whole thing back, and been very annoyed.
I seem to remember looking at this deal a few months ago, perhaps when Flibb bought his, and from memory, that did specify compatibles, because I thought about it and that, unless my memory is playing me up, is one of two reasons why I didn't go for it. So if I bought now because it said Dell toners and they weren't, I'd have been very peeved indeed.
All I need now is a version of that machine with built-in duplexing, and still at that price, and I'm sorted.