I don't know for sure, but this article from Carbon Credits suggests that (a) people can make money selling carbon offsets, and (b) the price you paid (a bit over 31€ per credit, not taking the time value of money into account) is in the right ballpark for buying credits in bulk and selling them at retail without totally screwing the retail purchaser. So it could easily be legitimate, and you could be getting exactly what you paid for.

If you get any replies to your identical post in the ecovillage forum at permies.com, please pass them along.