I am quite curious how you got 85million :O Ive never had past 2-3 million (in total...and that was struggling to save up for an FC house between me and my hubby)
In regards to farming, the problem I run into on my server is that supply far outweighs demand, and many folks undercut like mad. So when you do sell materials or gear on the MB, it tends to sit there for weeks or months unless you undercut as well and by the time all the undercutting ends you've ended up with half or less of the money you could have made had it not been undercut in the first place. Another problem I noticed is that a good chunk of the people that craft, have started gathering/farming their own materials (mostly with the help of retainers I'd imagine) and then just make what they need for themselves. They cut out the MB entirely. Sadly, I am one of those people though I dont craft. I helped my hubby get all his crafts to 50, and when I need stuff I get him the mats and he makes it. Once again cutting out the MB entirely.
Personally, I hate the MB and wish they'd have made it an actual auction house so prices were hidden until you bid enough, but thats just my preference and doesnt necessarily match the views of the rest of the population. I would estimate that about 85% of the money I earn is from doing dungeons, leves, challenge logs, and fates. Only up to 15% would be from actually using the MB. I'm only poor right now, cuz I gave most of my money to the hubby so he could finish materia-ing out his jobs/crafts. Before buying housing, my personal room, materia's for novus and lending money for hubby's melds, I had about 2-3million that I'd saved purely from dungeon/challenge log style contents.
