There are several low-cost eCommerce website platforms available that offer great features and functionality at affordable prices. Here are some of the best options:

1. Shopify:
Shopify is a popular eCommerce platform known for its user-friendly interface and extensive app store. It offers a variety of pricing plans, including a basic plan starting at $29 per month. Shopify provides a range of themes and customization options, making it easy to create a professional-looking online store. Additionally, it offers built-in marketing tools and supports various payment gateways.

2. WooCommerce:
WooCommerce is a plugin for WordPress, making it an excellent choice for those already familiar with the WordPress platform. It is an open-source solution, which means it is free to use. However, you will need to pay for web hosting and a domain name. WooCommerce offers a wide range of extensions and themes for customization and has a large community for support.

3. BigCommerce:
BigCommerce is a feature-rich eCommerce platform that offers various pricing plans to suit different business needs. Its pricing starts at $29.95 per month, and it provides a range of built-in features, including mobile-optimized stores, SEO tools, and secure hosting. BigCommerce also integrates with popular marketplaces like Amazon and eBay, allowing you to expand your reach.

4. Wix:
Wix is a website builder that offers eCommerce functionality. It provides a simple drag-and-drop interface, making it easy to create a visually appealing online store. Wix offers eCommerce plans starting at $23 per month, with features like customizable templates, secure payment options, and inventory management.

5. Square Online:
Square Online is a free eCommerce platform offered by Square, a popular payment processing company. It allows you to create an online store with ease, offering features like inventory management, order fulfillment, and integration with Square's payment processing. While Square Online is free, there are transaction fees for each sale made through the platform.

It's important to note that while these platforms offer low-cost options, additional expenses may include domain registration, web hosting, premium themes or plugins, and transaction fees. It's advisable to thoroughly research each platform's pricing plans, features, and limitations to find the best fit for your specific eCommerce needs.