There should be an option to refuse order from a potential buyer who has messaged you asking your service but you tell them you are not the right fit for it. They might not understand why you avoid them but still they want your service. For example, you say price is not agreeable and then they go buy your basic gig instead of standard.
So in this case the buyer might go and purchase something random emotionally and this would lead to further complications.Cancellations will hurt seller. I think introducing this option would reduce lot of unnecessary conflicts.
I know there is option to block but blocking someone right away can offend them. They might get another account and trouble you. Blocking also makes future sales impossible. We block basically fearing they would order something stupid. While refuse order option will make them at least converse with you and come to an agreeable conclusion. If they come to an agreement you can enable the accept order option in inbox.