I recently purchased wine in a store. The bottles of wine were packed tightly in the box. As I pulled out the bottle I wished to purchase, I broke two bottles in the box. Do I have to pay for the broken bottles and, if I do, how much do I have to pay since the store owner pays less than the price he charges. Do I pay the price he paid for the bottles or the price he sells them for?
Your first question is whether you are liable at all. In order to answer this question, we have to categorize your act of damage. The first point to make is that since it was your direct action which broke the bottle, this damage falls into the category of adam hamazik. We recall that the Gemara (Bava Kama 26B) states that adam hamazik is even liable for actions that are considered oness. Tosafos (Bava Kama 27B), whose opinion is the halachah according to many poskim (e.g. Nesivos 232, 5: R. Akiva Eiger (Responsa 2, 3)), proves that not every action that is classified as an oness is liable, but only those in which the one who damaged is somewhat blameworthy.
For example, if one went to sleep and while he was sleeping someone placed breakable items next to him and he rolled over and damaged them in his sleep, he is not liable. Another example, is if a person tripped over an item that was lying on the ground because he didn’t notice the object he is not liable because the Gemara says that people usually do not pay attention to what lies on the ground.
In your situation, had you been careful to take the bottle out slowly and carefully, the bottles in the box would not have broken. Therefore, you are liable.
Thus, we must consider your second question i.e. how much you are required to pay. From two cases which are discussed in the Gemara (both on Bava Metsiyo 99B), it is clear that one must pay the amount which the store charges for the damaged item.
One of the cases, which is relevant to us, is that the Gemara rules that if one steals from a store a cake comprised of fifty dates, where the store sells the entire cake for forty nine prutos but when sold individually the store charges one pruto per date, the thief pays only forty nine prutos and not fifty even though the storeowner can argue that he would have earned fifty prutos by selling them individually.
Since stealing is considered by Chazal a form of damage and is considered one of the twenty-four classes of damage, we can derive from the Gemara about theft that a damager pays the price the store charges for the item and not the amount the storeowner paid for it. It is obvious that if the storeowner charges forty nine, he paid less.
From this ruling of the Gemara, we can derive that if you only broke one bottle you pay the price the store charges for one bottle, but if you were to break an entire carton you would only pay the price which the store charges for an entire carton and the storeowner cannot argue that he would have earned more by selling the bottles individually. Tosafos explains that the reason we don’t accept the storeowner’s argument is that the Torah wants to be lenient with those who damage.
The Gemara does not explain its rationale, but from the question of the Gemara (i.e. why does the one who damaged pay only forty nine if the store can sell each bottle for one and earn fifty prutos), we can derive that the rationale is that one must compensate the one who was damaged for his loss and the price he charges is his loss.
Rav Eliashiv is cited (by Rav Mordechai Gross in Kovetz Teil Talpiyot (68, page 74)) as having ruled that one pays the price that is charged by the store. He was then asked how much one must pay if the store charges more than other stores and he ruled that one only pays the usual price. This can be understood as well since that is the true value of the object.
It should be noted that this does not work both ways. If the store charges less than other stores or sells wholesale one does not pay more than the amount this store charges since that is all the storeowner lost.
From this section of Gemara we can derive one further point. The Gemara says that when computing the amount the one who damaged must pay, we reduce the sales price of the object by the cost for any additional expenses which the storeowner incurs in order to sell his merchandise. For example, the Gemara rules that if when a store sells a barrel of wine the storeowner needs to hire someone to attach a spigot, this cost must be deducted from the sales price of the barrel. The reason is because this expense is included in the price and the storekeeper saved this cost when someone broke the barrel.
A practical application of this ruling is sales tax. When sales tax is included in the price of merchandise, since when one damages merchandise the store “saves” the sales tax, we must reduce the sale price of the merchandise by the amount of sales tax that is included in the price.
In conclusion, you must pay the price that is usually charged by stores or this store, whichever is less, minus the sales tax, if that was included in the price.