First wedding: Free, shot as a wedding gift, they did pay 2 nights lodging
Second wedding: $400. they got RAW images from the camera
Third wedding: $500, RAW images
Fourth wedding: Free, shot as a wedding gift
5th: $200, it was my cousin
6th: $600, friends of my husband
Now we charge $600 for a very basic wedding, and $1000 with more coverage and end products, plus we have some a la carte pricing.
It depends on the time involved, end products, and will it be just you or you and someone else?
I'd say charge them a very nominal fee and make sure that they know it's your first wedding.
Good luck!