(Affordable Scientology stuff is what they want the public to get hold of and make common knowledge because it puts them in a good (or at least reasonable) light . The expensive stuff is the stuff they hope does not become common knowledge. The truth about Scientology is to be found in their expensive stuff and mostly their secret or confidential material).
I'll explain what an implant is since this theme plays a very big role throughout the "advanced" processes of Scientology. An implant is a suggestion that has been forced on a person. The term "implants" would include a hypnotic suggestion as well. The idea is that as thetans we were given thousands of implants throughout our trillions of years of existence and that they have made us progressively weaker until we end up in bodies as we are now. If we can undo these implants, and especially the earliest implants, then we can become free of them and we will regain our former powers and be able to exist as thetans again.
(The fact that despite seemingly finding these implants and auditing them out never did give anyone these supposed abilities did not deter L. Ron Hubbard in the least. His attitude was that any process he invented worked and if it didn't work (which was always) then it was due to incorrect application or the person who did not benefit had committed crimes against him or Scientology or was by nature a suppressive person, opposed to the betterment of mankind. If you conclude from this that all Scientology processes must be extremely suspect and that L. Ron Hubbard was probably paranoid and totally mad then I will have succeeded in getting my point across).
More on the Implants. Some of these implants, the Helatrobus implants included, were supposed to have been disguised in blasts of electronic energy. A concept would be translated into an electronic signal and included in the blast of energy. The idea was to have concepts that nearly opposed each other and do this in a sort of sequence of varying opposites so that the last opposite was the same as the very first concept. The concepts then would have come full circle and they would effectively be in a knot that would stay there. These knotted up concepts would then make the thetan less powerful and could be used to control them. Hubbard's idea was to uncover the pattern of these implanted concepts and so undo the knot. Once undone the power of the person would increase to the point where they could find and undo more of these knotted concepts and eventually become super-powerful once more. Now in implanting these concepts there were more concepts then there are words now to describe them. Hence in identifying these concepts, words in English have to be modified to fit them, "absolutably seriousness" being an example and its opposite of "nix absolutably seriousness". You will read Mary Sue Hubbard identifying these concepts.
The "Between Lives Implants" lecture details Hubbard's claim that while he was up in the Van Allen belts as a free thetan he was mistaken for a person who had died and so he was whisked off to Mars to receive an implant (of a different type) to make him forget his previous life. He claimed he was nearly run over by a locomotive train while he was there are saw a fully armed space-cruiser ready to go on a punitive mission to Earth.
These lectures have been reproduced in full so that the criticism of quoting out of context cannot be levelled. You need to read the whole thing and think about it. Short quotations could be misinterpreted as quoting out of context or picking on a few imperfections to the exclusion of the rest in order to unfairly discredit the subject of Scientology. This is not what I want to do. To understand the bizarre nature of this claimed religion you need access to very full details. I invite you to read these lectures in full and draw your own conclusions.