Here’s something I found yesterday: https://www.presto.lk/worldwide/
The service gives each user a personal warehouse space in Florida, USA (which happens to be exempt from sales tax). You can shop with any US retailer, get the product shipped over there, and then request those to be shipped over to Sri Lanka, through FedEx.
There is no fee for the storage in Florida, and the FedEx shipping fee is solely based on the weight of the package. There’s a helpful calculator on the website that will help you figure out the fee: https://www.presto.lk/worldwide/calculator
You’d still be paying the customs tariff here, of course. FedEx will clear the item for you, and you will pay the applicable tax to FedEx when they deliver.
You can find out the tariffs that apply to different products on the Sri Lanka Customs website.
This is something I have looking for for years. Kapruka did something similar before, but they were limited to only a few retailers. They also charged a fee for handling, and didn’t offer to keep items stored in the US and consolidate them when shipping over here.
I’m going to try my Black Friday shopping this time on Presto.