These Ranks and Levels are awarded automatically, depending on your current number of sells.
There is a separate list that shows the Buyer Ranks
Level 1 : New
> 1 Purchase
Level 2 : Novice
> 5 Purchases
Level 3 : Apprentice
> 10 Purchases
Level 4 : Commoner
> 15 Purchases
Level 5 : Experienced
> 25 Purchases
Level 6 : Journeyman
> 50 Purchases
Level 7 : Skilled
> 75 Purchases
Level 8 : Quartermaster
> 100 Purchases
Level 9 : Master
> 125 Purchases
Level 10 : Grandmaster
> 150 Purchases
Level 11 : Loyal
> 175 Purchases
Level 12 : Noble
> 200 Purchases
Level 13 : Prince
> 250 Purchases
Level 14 : Duke
> 300 Purchases
Level 15 : Archduke
> 350 Purchases
Level 16 : Grand Duke
> 420 Purchases
Level 17 : Emperor
> 500 Purchases
Level 18 : Angelic
> 600 Purchases
Level 19 : Semi-God
> 700 Purchases
Level 20 : God
> 800 Purchases
Level 21 : Divine
> 1000 Purchases
Level 22 : Glorious
> 1250 Purchases
Level 23 : Demonic
> 1500 Purchases
Level 24 : Lucifer
> 1750 Purchases
Level 25 : Demon Lord
> 2000 Purchases
Level 26 : Ultimate
> 2250 Purchases
Level 27 : Unique
> 2500 Purchases
Level 28 : Refined
> 2750 Purchases
Level 29 : Exceptional
> 3000 Purchases
Level 30 : Rare
> 3500 Purchases
Level 31 : Nova
> 4000 Purchases
Level 32 : SuperNova
> 5000 Purchases
Level 33 : Legendary
> 6500 Purchases
Level 34 : Elite
> 8000 Purchases