There will always be someone who will do what you can do for cheaper. There will always be someone who does what you can do better than you can, at some point or another. The idea is that you can create a product, or market yourself, with the backing of an idea or concept that makes you stand out form the rest. People will buy what works as a general rule. We look for solutions. However if you have something that people can get behind, a reason as to why they should use you for a service or buy your product, then you can market yourself for whatever you want and people will be much more obliged to pay premium prices.
Big supermarkets do offer this service, but delivery prices are often very high or the food is warm or bruised when it arrives at the customer's home. If you own a large car, you could become people's personal shopper. Some people do not have time to run errands after a long day at work and others may not have the physical capacity to do so, so why not do it for them? You could also couple this service with others, such as:
You'll also need ecommerce software, fulfillment software, worry about warehousing, customer service and refunds. But that's not all. You'll also need traffic. Think search engine optimization, Facebook ads, and other social media campaigns. It is hard work, especially on your own. You could opt for Amazon's platform, which might be the easier route. But, then again, at the end of the day, this is a serious business, which could produce significant profits. So you're either all in or you're not.
Today, if you're at all serious about succeeding in any endeavor, whether online or offline, you have to deliver enormous amounts of value. Yes, you have to do the most amount of work for the least initial return. This is especially true online. Why? Because it takes time to build authority and create an audience, two primary ingredients necessary to succeed in the wonderful world of commerce on the web.