If your parents are paying for part of your wedding then it’s a moot point. Get them the album. If you are covering all costs don’t be afraid to tell mom that you need help paying for it.
It is probably less expensive to put the cost of a parent album in your photography package then to order it after the wedding, but ask the photographer to be sure. You could also limit the number of photos in the parents album to help cut the final cost.
And remember, it's customary to give your parents (and his) a thank-you gift at the wedding. You could make the parent album the gift. Or gift it to them for their anniversary or for the holidays.