In these modern times, many people already live together and have their own place before they actually get married and so there is a growing need for money on a wedding invitation rather than household appliances and treasures. However the way to request money is often considered impolite or difficult.
However there are other ways to tackle the issue rather than asking for the cash outright. Many department stores offer wedding vouchers which can be converted, so the couple can choose from clothes, food and household what they want to spend their money on. Alternatively a polite message explaining that specific items are desired such as a holiday will enable the guests to buy holiday vouchers.
In any case, today’s climate has left many people asking for cash and it is no longer frowned upon by most, so a polite message explaining the need for cash would be acceptable. If you feel that this is too cringe worthy, perhaps try a jokey message or poem explaining that the wedding itself has left you almost bankrupt.
Finally is none of these ideas take your fancy, you could have a Greek wedding or a “Money Dance” in which the guests pin cash on to the bridal dress in turn for a dance!