The Cost of a Gift
When giving cash as a wedding gift, it's customary to give what you would have spent on a gift. Traditionally, a wedding gift will cost $75 per person attending the wedding, though some gifts can be much more. Etiquette guru Emily Post suggests allowing your affection for the couple guide you.
Not every guest can afford a wedding gift from the registry, and most couples don't want friends and family to go broke at their expense. The Weddings of Today website suggests that a cash gift should be between $25 and $100, twice that if you bring a guest, depending upon your closeness with the couple.
Those who are uncomfortable with giving cash or uncertain about what's appropriate, or those with budgetary concerns, should look for a middle ground between traditional gifts and frugality. Give what you can, consider a gift card in lieu of cash and don't worry about breaking the bank to shell out a boatload of cash.