I do not scrape Amazon. That would be practically impossible, especially if you want to keep your costs low.
I utilize their product advertising API, which provides enough data for my needs (since I'm not interested in every single product and I only update once a day presently).
The manual part is figuring out how many units are in each item. For Lego, it's pieces. For Poptarts, it's individual pastries. For toilet paper, it's individual sheets of TP. Every product is slightly different, and it's often times not obvious. Once this manual part is done once for an item, I never have to do it again -- it gets an updated price from the API, calculates the unit price (because it already knows the total units), and then it updates the website.
I utilize their product advertising API, which provides enough data for my needs (since I'm not interested in every single product and I only update once a day presently).
The manual part is figuring out how many units are in each item. For Lego, it's pieces. For Poptarts, it's individual pastries. For toilet paper, it's individual sheets of TP. Every product is slightly different, and it's often times not obvious. Once this manual part is done once for an item, I never have to do it again -- it gets an updated price from the API, calculates the unit price (because it already knows the total units), and then it updates the website.