Quick answer: Include the item's price plus any real shipping or import costs, but skip temporary discounts. When in doubt, run through checkout on the merchant's site and use those final numbers.
Include the item price, plus real shipping
Our default shipping estimate isn't always accurate, especially for items shipping internationally or from smaller shops like Etsy or eBay. If combined shipping and import taxes add up to more than $10, add that amount to your listed price rather than relying on the default estimate.
The most reliable way to get this right: add the item to your cart on the merchant's site, go through checkout without paying, and use the final shipping and tax numbers you see there.
Skip temporary discounts
Don't price an item based on a sale that might expire. If a fan buys it at the discounted price but the sale ends before we can order it, the item can't be ordered. Only build in a discount if it's long-lasting, or you're able to check and update the price often.