With most couples' wedding budgets being squeezed (as everything seems to be at the moment), I think its best to start by talking about "value for money".
Since January 2010, palladium has been recognised as a precious metal, and it has its own hallmark.
Palladium wedding rings are a fantastic option for those with a tight budget. It has been mainly marketed as a gents metal, but it is possible to get narrow 2.5mm or 3mm width bands for ladies.
Good quality palladium wedding rings can cost as little as £125 for say a plain band, 5mm in width. Palladium is so popular as it part of the platinum family of metals. It is extremely hard wearing, its naturally white (so it doesn't need re-finishing at a later date like 18ct white gold), and it is extremely affordable. A platinum gents band can cost upwards of £700 for a similar style.
So for those who are on a tight budget - consider palladium.