There are ways and means of arriving at a cost that is beneficial and gives you tangible profit. In terms of hard product say furniture , appliances etc I am going to take you to a principle in marketing known as loss leading. This is where you look at the purchase price of the product and then check your competitor's price. You are prepared to create a price which is less than your competitor but enough to give you a good profit, thereby taking the lead in price market . This is a really good strategy if you purchase items in bulk or wholesale where you get them at a cheaper rate.
Another way to mark up your pricing is. The cost price plus your time plus the margin of profit you have in mind. When you have created that price you need to also match your competitor to see if you are on par, below or above. If it is above and you are satisified that you want it to stay at that price you must prove to your buying public why they should purchase your product above the other person's when it is the identical thing being offered. At this point you must be prepared that areas such as customer service is way above the competitor. I personally will buy something even if it is more expensive as long as I am receiving excellent customer service. Other areas to look at is the whole feel and ambiance that I get when I zoom into your business.
If it is an intangible service that you are offering you must be able to measure it by the passion that you have for it. That passion will drive you for excellency and professionalism.
Barber and hair salon: Measure this by the price margin within your area. Considering all the products you are using and create your price margin. Try to stay within that or just a little above.
In all these set up , never forget that your business reflects you and persons are looking for quality to go with the quantity. Don't short change them. Give value for money