What is the best cost services where there are no products;

I read the posts on the prices of wedding services, were actually very interesting, but I am asking for your opinion, your advice on something that really concerns me.
I have my own office and I provide exclusive services with a team of vendors to support me. My competitors have bridal shops, favors, invitations, equipment, etc. and in addition they are selling services. I can not compare my prices with them, when I should have my own prices for services only.
What is the best way of calculating the cost of my services;

Thank you