My boyfriend arranged this tour for us while staying in Hoi An. It is indeed free, however there is a 50,000 dong fee for the ferry ride and "tips" for the villagers. I completely agree with this practice of upfront donations, as it appears in the past only transportation was covered and then you were responsible for giving small change to the artisans or shopkeepers. Although we visited 5 locations, it was never assumed that we would buy anything, and neither were we pushed into feeling responsible to do so. We walked away quite happy with the fact that we spent a day mingling with locals (the most interaction is obviously with the Uni students due to their English skills), and we felt that it's a great way to give and take from a tourism opportunity.
Our one gripe was that there seemed to be a bit of confusion as to who was really leading the tour - it may have been the student's timid nature, but at times we waited around wondering about next steps and tour length in general, and the final stopping point of the tour, which involved a suggestion form, could have been resolved in a more timely and orderly fashion. Therefore, be sure to bring snacks with you! Otherwise, the guides were very eager to satisfy and will undoubtedly be next-generational leaders in Vietnam.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.