The price of one million kamas depends on the server, the game version and the timing. A single-account or recent server does not share the economy of a long-running multi-account server.
To sell fast, stay close to the best buy offer on your server. To maximize earnings, match the average sell price and polish your listing: clear stock, realistic delivery time and several payment methods.
Mind the minimum amount per trade too: set it too high and you lose small buyers, too low and you multiply small trades.
Right now, the best buy offer on the site is €3.00 / M on Kelerog.