My observation is that there seems to be a surplus of t3 goods (elixir, gems, and perhaps a little bit more so magic dust) and to some degree t2 goods (crystal, silk, and especially scrolls) relative to t1 goods. Smaller, newer players can often do well by producing more t1 goods in relation to t2 or t3 goods, then trading up.
My current plan for chapter 3 is to have 38 squares of marble production (8 level 9 plus 3 level 5 factories), 27 squares of crystal production (3 level 10 factories) and 12 squares of elixir production (1 level 4 factory). I play slowly and on a bit of a smaller scale, so you might want to add about 50% to those numbers for the average player who wants to push hard through everything, but I think the ratios will work. Something like 3:2:1 ratio for tier 1:2:3.