First, aim ya biz ni kumake profit so consider first the buying price. Price lazima izidi bei alolipia bidhaa. Second, what is the flow of the goods like, are they highly in demand and first moving? Hapo ndo profit margin varies. Where consumers can not do without the product a higher price will not stop their purchase. Lastly what's the market price? How are other sellers doing it. Ikiwa seller A yuauza kitabu at Ksh. 50 and Hassan's books are of the same quality as that of Seller A, selling at a higher price will see him having dead stock coz definitely buyers will go to seller A. Selling at a shilling or two less may lead to attraction of more customers. This too largely depends on the product in question. Good luck pricing and selling Hassan.