How Do You Create Cost-Effective Images For GMB Postings?

In the 250th episode of Semantic Mastery's weekly Hump Day Hangouts, one participant asked how to create cost-effective images for GMB postings.
The exact question was:
Good Day Gents thanks for offering this Forum to help us. My question is how do you guys create images for posting to GMB's? If you are posting 4-5 times per day that's a lot of images how can that be done cost effectively and efficiently? What would that cost approximately? Thanks
