Sorry but this has been bugging me and i have looked everywhere and haven't found a single reference. Money markers in Road to legend are worth 100 coins? Or 100 for each player so 400 in total?

They are worth 400 per marker at all campaign teirs.

Isn't that much? Anyway, have played only 2 sessions but it does seem that the players get enormous rewards in every dungeon compared to the overlord that his only hope is to actually kill some players but i guess i will have to see how it goes.

the coins are a pooled amount shared amongst the group and it does get expensive when they start trianing for skills and traits so the money doesnt go far. Specially if they want to start buying group items like the guides and city upgrades.

+1 for Tundrra. The heroes do get a lot of money, all of which gets put in a communal pool. It doesn't last long when they start buying things. Also remember that you can't buy random treasures in the Advanced Campaign, you're stuck with whatever's available at market.