A little boy asked his father, "Daddy, how much does it cost to get married?"
And the father replied, "I don't know, son, I'm still paying for it."
Should you have a marriage contract? It's a misleading question, as pointed out by the National Resource Center for Consumers of Legal Services. The fact is, if you're married, you already have a marriage contract. Your marriage contract consists of the obligations imposed on married couples by the inheritance and domestic relations laws of the state where you reside. Romantic or not, there is a marriage contract. The only question is whether you like the "one size fits all" marriage contract provided by the state or whether you want to substitute your own contract.
People routinely change the state law provisions for inheritance rights for married couples - they write wills, often giving the entire estate to the surviving sposue. This is common, socially acceptable, and even encouraged. Marriage contracts and pre-nuptial agreements settling other property rights, however, are still uncommon.
Not that marriage contracts haven't been around for thousands of years, mind you. Just imagine the tribal chief striking a deal with the neighboring chieftain over the dowry to be given with the bride.
My personal favorite is the Jewish marriage contract or Ketubah which has been in use for centuries B.C.E. to the present day. "Be my wife in accordance with the law of Moses and Israel. I will work for you; I will honor, support and maintain you, as it becomes Jewish husbands who work for their wives, honoring and supporting them faithfully...." Additionally, the Ketubah (1) outlines the obligations that a husband must fulfill in marriage -- to honor his wife, to provide the necessities in life, such as food, clothing, and shelter, and to fulfill his wife's sexual needs; and (2) it specifies that he will pay his wife a particular sum of money in the event of death or divorce. Not bad.