You can check occupied houses in the neighbourhood to see how much money they have. There's also an option - which came with an EP but am not sure which one, Nightlife maybe - under 'ask' - 'how much money do you have'.
I don't know how much money a sim needs to have to be classed as rich under that want though.
I've found that asking them how much money they have is next to useless- they lie all the time. Someone who gave me 4 $$$$ symbols had maybe $12000. The one time actually married a sim with ($50000 is the requirement) they'd said $$ when i asked them. --- you fat bastard you fat bastard you ate all the pies
Ok so Cassandra Goth is rich. I maxed out my affection with her and she moved in with me but I don't have the option to propose. Under her wants it says she wants to get engaged but I can't. Any ideas?