I do not interpret Brandon’s coin toss at the end of S&S2 to be sending ‘the implicit message that wealth is the most important thing in the world, and Marianne married not for love, but for financial security.’ At my first viewing it appeared an old wedding custom like throwing rice has been a custom in modern times. In The S&S Screen Play and Diaries, page 202, Emma Thompson explains the coin toss:

According to the custom of the time, BRANDON throws a large handful of sixpences into the crowd, and the VILLIAGE CHILDREN jump and dive for them.

I researched (if I may use so lofty a word for googling!) wedding customs and decided it is a truth universally acknowledged that grooms tossing coins into a crowd of well-wishers is a custom whose origin is either to be found in Ireland, Scotland or both, begun either before our era or by the Victorians. In other words I found the custom listed on many websites, sometimes termed the Irish Grushie, the origins sometimes rather misty and none with scholarly references. Some information from one site:

The word Grushie in Scots means 'healthy and thriving', so in truth, this tradition is about prosperity and getting the bride and groom off to a good start. The best way to do that is by giving back a little. At the end of the ceremony as the bride and groom are to step into the carriage, the bride will throw her bouquet to see who may indeed be the next lucky bride. …for the men, there is the Grushie, which was traditionally a handful of coins tossed alongside the bouquet. The person who tossed it was generally related to the groom, his father, elder brother, sometimes the Best Man and even upon occasion the groom himself.

http://www.articlesnatch.com/Article/The-Irish-Grushie-Or-Wedding-Scramble---A-Celtic-Tradition/3281816