In today’s highly competitive market of consumer products, customers have the opportunity to compare and choose among the products of a considerable number of companies. Considering the relatively high waiting cost for products and close substitutes among competitors, customer always faces one question whether to join and wait in a selling system (or online shop) upon arrival or to balk the system for another one. By a certain reward-cost function which reflects his reward after service and the inevitable sojourn cost, he seeks the individually optimal strategy to maximize his benefit against other customers who have the same benefit function. The individually optimal strategy is also called individual equilibrium strategy. Such self-organized or endogenic equilibrium unveils differences in individually-optimal and socially-optimal behavior and thus be used in modelling various issues arising from operations management and service pricing, to mention only a few.