What margin do on products in the online store

Many suppliers of goods in their price lists indicate the recommended retail price (RRP).  This allows you to maintain healthy competition in the market.  But what to do when the supplier does not indicate retail prices.  What margin to put on the product, so as not to alienate customers and at the same time make a normal profit?

Markup for some product groups

1. Costume jewelry, accessories, souvenirs - 100%
2. Gadgets - 30%
3. Accessories for gadgets - 100%
4. Clothing and shoes - 45-105% (depending on the season, type of product, quality)
5. Everyday products: hygiene products, household chemicals, detergents, underwear, and pet food - 10-20% (we are talking about brands that are sold in mass markets, not about niche ones)
6. Toys - 20%
7. Digital and electronic equipment - 50%
8. Products - 50%
9. Building materials - 50%
10. Car parts and accessories - 30-35%
11. Cosmetics - 75%
12. Office - 25-75%
13. Bed linen - 30-50%

Knowing these data you can approximately calculate the purchase value of the goods.  For example, your competitors are selling a specific phone model for 6000 UAH.  30% of 6000 UAH is 1800 UAH.  Approximately the purchase price of the phone will be 4200 UAH (6000-1800).  The calculations are very approximate, but nevertheless, resellers cannot exceed 30%, otherwise customers simply will not buy goods.