If the shop or seller is new to me, I usually bargain hoping to get the best and lowest price. Regardless if it’s been approved or not, I still buy it most especially if the product is very useful for me. However, when it comes to buying from an old shop, or the particular shop where I mostly buy, I don’t apply bargaining at all. Simply because I trust them already and I know their products already. The fact that their products are definitely worth of its cost, I usually do not bargain at all.
Most of the time, when you buy things from a regular shop that you usually bought items you trust them already with th price though sometimes I personally ask if there's some adjustment or some discount that can be provided if there's then I thank the person if there's none then I continue to buy as I know that the quality is fair enough for my money, just like you said, it was the trust that you already established that matters when buying an items.