if you are creative you can make a shadow box featuring their wedding invitation or a wooden plaque that you paint- shellac on the invitation and then get creative with some border word around the edges of the invitation.
another neat idea and very frugal idea is to find out what their song is they will be dancing to- and find the lyrics on the net – type them up nice way in a nice font and print it out along with their names and date of their wedding and frame depending on thier tastes you can use an assortmant of different styles of paper to print it out on.
or can even just frame the sheet music, maybe “age” it first in some tea,if its not too long a song and
has maybe just 2 pages of music .
if not creative hit the clearance areas at the bigger name usually $$ sept stores they often have stuff that is 75% off plus you can sometimes use a coupon to further your savings .