wren: A friend of mine got married this last summer and got a box of invitations at Goodwill for about $5. I've also seen boxes on clearance at Staples (Westwood) within the last week or so. She asked my mom to do her flowers, gathered a hodge-podge of vases/containers from friends and just shopped 2 days before for flowers at the Burien Farmers Market. My mom did it for her for a wedding gift, no charge. (She's not a professional, but loves to do flower arranging). She's also in a choir/singing group and they all sang at the ceremony. Her husband put a playlist together on his computer for music at the ceremony and I couldn't even tell there wasn't a DJ.
My husband and I owned our own businesses when we were married, don't know if it's an option for your daughter but we did a few trades for our event -- I bought the flowers and the florist traded me for her services, same with the printer for our invitations and thank you notes, we also had a dear friend who put up some of our relatives (on his timeshare credits) as our wedding gift. We used an outdoor, public space and only had to pay for a permit from Parks and Rec & rented some chairs.
If she has some close friends or aunts that ask her directly what she might need/want (for a bridal shower or the wedding gift) she can also ask if they might want to buy say.... her wedding shoes or her veil or whatever, you can get very creative. Have a friend be the photographer or videographer (it's amazing how genuine and authentic a non-professional video can be) -- the best photos of my wedding were the candid shots by friends and family and we actually never did order any photos from our photographer, just kept the proofs/albums.
Above all, have fun with it and enjoy the day, it'll be the fastest day of her life.