Retailer price-matching policies, which promise to equal or beat a competitor’s price before a purchase (or in some cases, after), can protect you from overpaying – if you can get through the fine-print exceptions.

Some purchases are ineligible, including clearance items, those from opened boxes, special orders and items available for a limited time.

For example, Staples retail stores will match prices of other walk-in stores, but not those of online retailers except Sears won’t price-match Internet-only retailers.

Just understanding the policies can be a chore. Lowe’s website advises visitors to go to a store for complete details of its everyday low-price guarantee.

Earlier this year, the Better Business Bureau recommended that Toys R Us modify or remove in-store banners that could mislead customers into thinking that its price-matching policy applied to online prices.

Read store policies carefully, especially if you’re counting on price protection, which promises to reimburse you for the difference if you find a lower price within a certain period after making a purchase. If you’re unsure whether a price guarantee applies at a walk-in store, call ahead before venturing out.

If a retailer rejects your request for a post-purchase price adjustment on an item you haven’t used, find out if you can return it under the store’s regular return policy. Also check your credit card; some offer price protection.