If the words ‘local’ or ‘cheap’’ are added to a search term it means that:

Adding words like "local" or "cheap" to a search term indicates higher commercial intent. A user searching for "cheap local shoes" is likely further down the purchase funnel than someone searching for "shoes." They are actively looking for a specific type of product or service with a clear intention to buy, making them more valuable to target. The keyword itself won't automatically become cheaper; its cost is determined by competition and Quality Score. Adding them as negative keywords would prevent your ads from showing to these highly engaged users, which is counterproductive. Finally, the user is more likely to take action, not less, due to their specific and often urgent needs implied by these modifiers.