There's something of an oddity I've noticed with the MB on my server. There are certain sellers belonging to the same company that, without fail, will always have a particular type of item posted on the MB. The moment it's sold, it's almost instantly replaced, and if you put up your own listing, it's undercut within five minutes (drastically so if it's been over a day), no matter the time of day. It's nigh on impossible to sell any of said items if you do anything other than sit beside the summoning bell all day, to the point that despite being popular items overall, they have the only listing, I'm assuming because others have given up. I looked up said players several times over the past few days, and they are always on, and always gathering/ crafting. It was going on before I took a break in early March.

Could they be gil sellers? I initially thought it could be crafters looking to make a lot of money pre-SB, but as far as I can tell they don't do anything else, and judging by the time scale they'd have more money than they'd ever need.