Should i create my wedding poster design online ??

I have visited many wedding planners for my wedding poster, I want to create attractive wedding posters for my wedding. The wedding planner all those I have met, use to create wedding poster designs on the online graphic design software, where they have the option to customize their pre-defined wedding templates easily. Now I am confused that if they are creating online then why should I give them a charge to just design my wedding poster, rather than I am thinking that to make my own.

Suggest to me what can I do for creating my attractive wedding posters.