This article presents mathematical model results for items that are not immediately deteriorating, and the service life depends on the item's price and availability. The main purpose of this work is to increase the business industry benefits. Here we are developing an inventory model where demand for a product is actually driven by inventory. The developed inventory model is widely applied to products such as food, electronics, cosmetics, clothing, fashion, merchandise, fruit, etc., where price and inventory play a very great role in demand. This reinforces the idea that inventory plays a key role in helping shoppers select a particular product from an assortment. Through numerical exploration and sensitivity analysis of the proposed model, we describe the behavior of the stock model using the particle swarm optimization method by determining the optimal order quantity, optimal order time and selling price, as well as determining and maximizing the gross profit.