Use common sense. Look at the product and respond two questions "is this a normal price for shoppers?", "would you buy this product for the set price?" People should agree to pay you the price you ask for. When we say that some prices are high (I'm sure at least once you said that), it means we're not ready to pay the price as perceived value is low.
How to identify low perceived value? Your ads result in engagement but not orders. People like, comment, share your ad, visit your store and leave abandoned carts.
I'm saying about a situation when your website looks nice (high-quality pictures, good descriptions, visible buy button, etc.) and there is no reason for real-time visitors not to buy but they still leave with no purchase.