Different section here are always going to have different prices.
All of them might be close to this "rule of thumb" you are referring to, which I'm perfectly aware of by the way, just so you know

Counter-Strike forum are selling for around 1:80 right now, some even lower.
While you have the Magic the gathering section that are between 1:90 to 1:100.
Archage is very complicated because Trion is very good at shaking the market with their in-game shop.
I think a lot of the adjustment in the current market here on D2jsp is due to the new boxes.
I am not a fan of their 'Pay-to-win' system they are reveling more and more as time goes by.
As an example:
1x APEX is 1200 credits.
That is nearly 3 boxes, and lets play with our mind that it actually is 3 boxes (60 Credit missing for the last box).
If you are lucky enough, you can get 9 rumbling archeum trees.
3 per box. (With luck).
That is on my server 50 gold per tree and 150 gold per box.
This would add up to 450 gold per APEX if you sold the containing items.
And poof! 1:45 ratio. ($ to gold ratio in-game)
But this is just a lucky scenario.
I usually receive 1 per chest so I'm not sure if we can go a head and say '2' would be an average number.
But if it would be, Melisara EU would have the ratio of 1:30 if you pay directly to Trion in order to purchase these boxes with Apexes.
Now the ratio would be very different paying with the credit option.
$5 would be 900 Credits and that would be two boxes.
Point is,
The FG:IGG ratio for Archeage will always change.
Both up and down. It all goes down to what Trion chose to have in their own shop.
This post was edited by Spetch on Nov 13 2014 01:30am