Who charges what?

Perhaps the retailer get a slightly bigger slice from the cake, and the designer and the wholesaler less, but your estimates don't seem very far removed from reality, I think. Maybe one of the publishing guys here can fill us in on the details?

As for the percentages, and the way the designer gets his money: it depends on the contract. Most contracts I've seen give the designer a percentage of the wholesale price, which roughly is half of retail price. Say a designer gets 5% of the wholesale price, for a game that retails for 30 euro, that's 5% of 15 euro, which is 75 eurocents. That's not a whole lot, is it? :) Of course, if you have a particularly promising design, or if you have made a name for yourself as a designer, you might negotiate a better deal than that.

There are a lot of possible contracts variants, % of wholesale price per game is just one of them. Other possibilities are: % of profit, a fixed price per game, or simply a one time sum of money regardless of how many copies sold (you'll regret this one when the game becomes a million seller, though ;). You also might negotiate a better % when the games sells over a certain number of copies.

Also of importance is how long it takes before the rights to the game revert back to you. And then there are the little niggly bits you may want to have in your contract such as: do you have veto right on design decisions, does your name get on the box, do you get to proof rules and images before they go to print, etc, etc?