if the security door hinges are common, you can buy a pair (3 pieces) for more than 1 yuan, and the better ones are more than 2 yuan each, and some of them are patented hinges, which is even more expensive.
In general, the price of the hinge is between 1~2 yuan, because he has installed one less, so he can deduct some money according to the quality of the hinge. Generally, 1~3 yuan is enough.