There are many options to add a shopping cart to your website. These are complex and take time to fill with products so this option does require more time and the cost will increase.
I build websites for people who do not want to spend a fortune and for those who are happy to do there own work to save money. The choice is up to you, pay me or do yourself.
One of the largest shopping carts is WooCommerce They have many options and tools, from free to costing money.
