Your ecommerce website is at least as important as your informational website. In many cases, they are one and the same. It's gotta be right. It's your virtual storefront, and it's accessed by people all over the world. It must function correctly, intuitively and in the most simple manner possible.
Your chosen ecommerce platform must be a professional one. There are many options for ecommerce platforms with shopping carts that work perfectly, all you need to do is choose one that you feel comfortable using. If you need an outside party to update your products on your own site, you've chosen the wrong site for your needs.
The ecommerce solution you choose doesn't need to be complicated, expensive or fancy. It can even be FREE. There are many ecommerce platforms that are free to use. They might not provide you with an opportunity to fully describe your business on various pages, so these free ones are often linked to from a "shop" button in your regular website's nav menu. Still, this is a common practice and if you can create an aesthetically consistent user experience between your regular website design and your ecommerce website design, you will see very few drop-offs and a higher conversion rate.
And, re-reading that last sentence: if you don't understand what I'm talking about there, you are definitely in need of my services.
I can listen to your needs, make recommendations, contrast and compare ecommerce platforms for you, help you set them up, make them look pretty and function properly, and populate your shop with products.