I believe the page likely belongs here. Regrettably, scamming is a big part of the game and I don't think you can (or should) ignore something like that on the fan wiki page.
You make it sound as though people come here specifically to learn how to scam, or how to avoid scams. I would have to question how much traffic we get in either regard. As it stands, I think the page is an interesting account of all the sorts of scams (and the attempts to thwart them via patching) seen through the history of Growtopia.
It does look like it could use some touching up though, there's some repeats and things that could really be combined together (like the fake moderator application, which should be covered under phishing... but in fact, most of the "phishing" examples listed are not actually examples of phishing).
Much of what is there could probably be condensed down. A lot of basic concepts are over-explained with too many unneeded examples, along with splotches of personal commentary about scammers and victims alike that really serve no purpose.
Pricing is always "Whatever someone is willing to pay"
It's never the same, so having a page that defines a price is admittedly a little silly.
However, it can be useful to get a general idea of how much things are worth in relation to each other. It is true that such pages can be easily manipulated by those looking to exploit the page for profit, but this is a community page and it can be moderated by the knowledgeable members of that particular section of this community. It's not likely to ever be truly accurate, but it does provide another option for people looking for pricing, aside from visiting worlds like HONORS.
I would say that perhaps the most useful aspect of these pages was the disclaimer that (used to? people frequently deleted/altered it) explains the fluidity of prices, and to not trust any single source on the matter as they can easily be manipulated by single parties for profit. It was also convenient to direct members to such pages when they would repeatedly try adding pricing to specific item pages. Just as a "No, don't put that here, you can stick it over there if you want."
I don't know if such pages exist on other wikia sites. It seems reasonable to remove such information, as we already sternly remove it from item pages themselves. I am not sure if it is necessarily beneficial to remove it, though.