In European countries, people are used to fixed prices. What you see is what you pay. This way, the customers do not have to think about how much something will cost them or calculate how much money they will spend in the end. However, this is not how it is in Egypt.
It might be frustrating for someone who is not coming from a world where bargaining is an everyday occurrence, but you will have to get used to it if you wish to purchase something here. Haggling is like riding a bike, the more you do it the better you will be at it. Haggling is considered to be part of the local culture in Egypt and visitors should get used to it.
In order to understand what the right price to start bargaining with is, it is usually 50% less than the first offered price, but in some cases, one can also start as low as 20% of the first offered price. It also depends on what are you planning to purchase. When it comes to souvenirs, you will be asked for as many as €10 per souvenir, and in the end, you will pay as low as €1 or €2.
When it comes to essential oils and perfumes, if you are buying them in the right places then you will not have that much space to bargain as you are getting a top-quality product and Egyptians will not lower the price significantly.
If you are visiting places such as the Pyramids of Giza or Luxor, places popular among the tourists, ask your guides about the best shopping places there as they will know places where you will not overpay.
All in all, prepare yourselves and do not lose your temper. One must always be kind and polite. After all, you can always leave without buying anything.