The Royal Kingdom Challenge

I'm considering introducing dowries to the game, since my second generation sims are about to start to get married. Anybody that wants to contribute with ideas? What are good sums for climbing the ladder? What rules should be applied?

Something like:
50 000 simoleons for merchants or peasants to marry 1 step up
100 000 simoleons for merchants or peasants to marry 2 steps up

Any ideas and thoughts are welcomed :)