I think you are asking the wrong question. The real question is how to validate that customers are even interested in this service at all, and can you deliver it at a sufficient scale to be profitable in the long run. You are not really concerned about profitability in the beginning, so you're mostly pricing just to get the most customers possible to validate your hypothesis. Then, once you have a consistent, albeit small, demand for your service, you can begin to explore ways to scale and make delivery more cost effective.

Also be careful of learnings collected from early adopters. You'll run out of them eventually, and may need to adjust some of your business to serve the mass market. Best to figure out early how these early adopters differ, and how that affects long term profitability, even if you don't leverage that in the service right now.