I have a mobile which my father had bought in Rs.10,000 ($95.49). Now I want to sale that mobile. We went for its market price and the shopkeeper rated it Rs.4000 ($38.19). Is it permissible for me to sale it over more than the original price or more than the market price?
You can sell it more than the original price if the price is fair and you are not making use of the ignorance of the buyer with the real value.
The Companions used to make advice to those they sell to, saying this is worth so and so, a Companion refused to sell his horse with a big amount of money advising the buyer that the horse is worth much less than the buyer was willing to pay. So, you can profit from selling the mobile but be fair and make the profit reasonable.