The claim should be broken up into pieces:
Did Mr. Hubbard write or publish that the way to make a million dollars is to start a religion? Obviously not, or his writings would have been cited, but that's fairly obvious and not really helpful.
Did Mr. Hubbard state verbally (publicly or privately) that the way to make a million dollars is to start a religion?
The page you have linked cites essentially all available evidence that he did. All of it, of course, is hearsay and hardly conclusive one way or the other, as you correctly pointed out in your question.
It is worth noting that the page you cite, while it does mention evidence (dueling affidavits) counter to the conclusion reached, has failed to examine all available sources regarding German courts' actions in respect to the claim:
I believe that these dueling affidavits have met in court. Stern, a German magazine, was sued by the Church, and the suit was thrown out of court after they obtained the Moskowitz affidavit.
It's unclear if this is presented simply as a belief (as implied by the first sentence) or as a fact (as implied by the second), because no evidence or source is provided.
The Church of Scientology has published an article devoted to debunking this claim. Included therein are two documents purported to demonstrate the Munich court's rulings on this subject: a 1982 Munich Court judgment and a 1986 Munich Court judgment. They are not in German, but appear to be credible scans of translations of relevant document. The Church summarizes them as follows:
In 1982, a Court in Munich, Germany, found that L. Ron Hubbard never made the statement and enjoined a German publisher, on penalty of a fine or jail sentence, from printing the claim. (Landgericht München I, case no. 9 0 19 087/82, 1982 ) In 1986, the Church of Scientology of Bavaria also obtained an injunction against another German publisher prohibiting republication of the falsehood. (Landgericht München I, case no. 9 0 17718/86, 1986 )
The evidence so far, while it might be enough to discourage litigation-shy publishers from making the claim, isn't definitive, of course. It still amounts to, "He said ____," and "No he didn't."
We can, however, go a little further in this by examining some of L. Ron Hubbard's relevant statements on the nature of religion, Scientology and money. I would expect to find evidence of such an attitude expressed directly or indirectly, if the original claim were true. While not directly evidence for or against the claim, these statements are given to assist the reader in evaluating the likelihood that L. Ron Hubbard made a statement about earning money by starting a religion.
In other words, these are evidence relevant to the question:
Did L. Ron Hubbard believe or act upon the idea that the way to make a million dollars is to start a religion?
In a interview carried out by writing and published in Rocky Mountain News February 20, 1983, L. Ron Hubbard wrote:
A thing most people don't know is that it was Scientologists who elected that it be a church and so it became. I actually never founded it, although they call me Founder because I founded the subject, not the organizations. Because I like to help people, I helped them all I could, up until 1966, when I resigned. I still research in this field and still write books about it. I still get mail bags full of letters every week. They are actually doing great and I wish them well.
In a 1970 article, "What Your Donations Buy," L. Ron Hubbard wrote the following:
Occasionally some church or mission goes on a big kick of high pay. We very soon pull the rug out from under that. So if your donation went that way for a brief period we corrected the outness fast as we frown on money-motivation like a thundercloud.
Some fringe fellows know that if you had a complete monopoly on the only workable mental technology on the planet you could make billions. That's why they're on the "fringe." So we prevent your donation from going in that direction.
There is another statement he's made about money and Dianetics that I've encountered before which remains elusive just now; I'll add it if I come across it.
It should be kept in mind that Scientologists understandably perceive this claim as an attempt to undermine the legitimacy of their religion by degrading it to a money-making scheme on the part of the Founder. So the claim is not exactly innocuous; it gets into religious discrimination (or justifying such) very rapidly.
My own conclusion:
I do not believe L. Ron Hubbard ever made such a statement, though I would believe it of many of his contemporaries. The evidence is sketchy, and I don't even think he particularly cared about money, based on examination of his writings and stated opinions. The motivation for those originally making and repeating the claim appears to me to be disparagement without particular concern for accuracy.