What you charge for meal plans will depend on many factors such as your business, target demographic, location, their income, your own level of expertise, how customized the meal plan is, how long it took you to put it together, etc.
There is no right or wrong answer and sometimes you have to play with pricing to get it right. We recommend doing some research into what other similar professionals are charging. Many of them list prices for their programs on their website.
Here's some additional resources you may find helpful: