Generally speaking, if you will be attending the wedding, plan to spend $50 – $100 on a wedding gift. This amount represents a gift from one person; thus, if the gift is from a couple the value would be in the $100 – $200 range.
If you are not attending the wedding but wish to send the couple a gift, there are no guidelines pertaining to value; however, it is not uncommon to spend less on a gift for a wedding you will not attend than on one which you will be attending. As an additional note, it is not actually necessary to send a gift for a wedding you are not attending, though many choose to do so. And finally, wedding gifts may in fact be sent up to one year after the wedding date.