Grades = Price and not necessarily = better quality. And manufacturers / tanneries will grade their leather/pricing differently. Grade 1 maybe a top grain aniline dyed leather with no protective top coat; this is a very soft-hand comfortable, breathable leather but will soil very easily. Grade 3 maybe a top grain pigmented leather that has a protective top coat, doesnt breath as well but easily cleaned. Grade 2 maybe somewhere inbetween. But all top grain leathers are your most durable and most expensive. But is worth the investment.
Its possible to purchase a top grain leather sofa-loveseat-chair starting at 3200.00

Here is a link that might be useful: leather sets for 3200.00