In the introduction stage of the product life cycle, the most commonly used product pricing strategies are either penetration pricing or skimming pricing. Penetration pricing involves setting a low price to attract customers and gain market share quickly, while skimming pricing sets a high price initially to maximize profits from early adopters before lowering the price over time. The choice between these strategies depends on market conditions, competition, and the company's overall marketing objectives. Reference: "Principles of Marketing" by Philip Kotler and Gary Armstrong discusses various pricing strategies in the context of the product life cycle.