The definition of "value" is entirely subjective. The value of any said product, based on a concept created by Karl Marx, is determined by six influencing factors: wages and salaries of workers, profit made, interest on the product, any kind of rent paid for facilities used, taxes, and fees (including royalties). The product value is determined by the item's cost of production and the function of the item to the individual consumer. An mp3 player, for example, would be determined by its usefulness to the consumer - does it hold music? Video? Photos? This value, plus the manufacturing cost (materials, labor, facility fees) make up the product value as determined by this concept.
"Market value", however, takes into account the economy, the knowledge of the consumer and the time at which it will be bought. The value of that product is dependent upon the market into which it is thrown. In the current market, some products are latched onto and become trendy, and it doesn't give other products of equal usefulness the opportunity to succeed. Which would you rather have: an iPod Nano, or an RCA mp3 player? Would you rather have a MOTOROKR or a random Kyocera cell phone with a built-in music player? Would you rather have a tee-shirt from Hollister, or a tee-shirt from Sears?
Market value leaves room for competition. The product that get the trendiest the fastest is named with the highest price. The thing is, people would rather have that product so much that they're willing to pay the market price, even though its true product value is much lower.
Finding market value is much more difficult than finding product value, because an audience must be continually surveyed. Market value depends on the trendiness of the products combined with their product value. Ever-changing consumers will want the trendiest product available, and the research put into a product's market value will help the product to do its best in the current market.
