Idea against Undercutting at the Marketboard (The next.. )

[Sounders]

Ehcatl Sealants are easy to acquire and those were 350k on my server for months. They've only recently started tanking.

Nope. I disagree with you. Ehcatl Sealants is one of the most annoying things to acquire. Each sealants need 8 oaknots, so in your server, it means oaknots is around 45k each. And you can only have a maximum of 6 per day.
For mastercrafters, the effort to do the ixal quests just to gain 45k is not worth it. The effort in doing ixal quests is almost the same as doing a 4-star. So mastercrafters, don't want to be bothered with getting the oaknots themselves, it's better to buy them at mb. Of course, there can be exceptions that mastercrafters have spare time that they'd rather do beast tribes than craft.

[Sibyll]

snip

I'll agree to disagree then. I've only recently been able to 4* craft and only for BSM and ARM, so I really can't comment on how profitable these will be. Looking at the market board those items aren't selling very fast (I'm also on Mateus by the way). So to me it's a guaranteed return of Ehcatl Sealants for those dailies over the given time investment versus a piece of armor that may or may not sell for 900k.

I could see your argument making more sense for a 4* crafter that can make Artisan/Forager gear because the market for those is likely stronger than for DoW/DoM, at least on our server. However, this is just my speculation from looking at the market board so if you have any incite on our server economy I'm open to hear it.