The best bargain in my life was buying jeans from Gloria Jeans a year ago. I still wear them and I like them. I bought them on sale and they cost me only five hundred rubles. As the example, usual jeans in that shop are worth about two thousan rubles. So that was by best bargain. Really cheap jeans, which have a good quality.
В предпоследнем предложении не by best bargain а My best bargain