SEM means search engine marketing, which includes paying for ads to show up in search results. When your product is cheap, it becomes harder to profit from paid ads because the cost of getting a click can sometimes be close to what you earn from a sale. The way around this is to either increase your average order value, meaning get customers to buy more at once, or focus on repeat buyers who come back often. Some low cost product businesses also use ads to build an email list instead of going straight for the sale. Do you think paid search can work for very low priced products?