It's difficult to say when bargain shopping first began. The earliest shopping efforts were probably about trading: a buffalo skin for a winter's supply of food; a rifle for a mule; a homemade apple pie for a petticoat. It was about supply and demand. And when the supply exceeded the demand, the price went down: bargains were born.
The first recorded resale activity for clothing was in Paris in the early 18th Century. True to Parisians' reputation for being fashion-forward, the "resale" clothing (in addition to fashionable fabrics, lace and jewelry) was actually stolen from the upper class and sold in the lower class underground for a fraction of the original cost (hence the term "getting a steal"). In fact, 28% of the criminal cases tried in Paris in 1710 involved stolen clothing.
The practice became very popular and was later legitimized via taxes collected on the hundreds of resellers doing business, according to tax rolls of the time. Since clothing revealed the "harmony of the inner and outer man", clothes became the highly desirable "..weapons in the battle of appearance", according to The Culture of Clothing. Some things never change. You are what you wear; the mode of acquisition is immaterial. Tres chic!