The list is ordered from the oldest to the most recent announcement made by the Riot staff regarding skin sales.

Pre-Seasons Seasons
Pre-Season One Season One
Pre-Season Two Season Two
Pre-Season Three Season Three
Pre-Season Four Season Four
Pre-Season Five Season Five
Pre-Season Six Season Six
Pre-Season Seven Season Seven
Pre-Season Eight Season Eight
Early Sales


Period Sales Link
September 13
2011
September 16
2011
Pantheon RuthlessCircle Ruthless Pantheon [S|L] - 50% off
Kayle ViridianCircle Viridian Kayle [S|L] - 50% off
Gragas Gragas,Esq.Circle Gragas, Esq. [S|L] - 50% off
[1]
September 16
2011
September 19
2011
Karthus PhantomCircle Phantom Karthus [S|L] - 50% off
Malzahar VizierCircle Vizier Malzahar [S|L] - 50% off
Brand ApocalypticCircle Apocalyptic Brand [S|L] - 50% off
[2]
September 20
2011
September 23
2011
Udyr BlackBeltCircle Black Belt Udyr [S|L] - 50% off
Katarina BilgewaterCircle Bilgewater Katarina [S|L] - 50% off
Nasus DreadknightCircle Dreadknight Nasus [S|L] - 50% off
[3]
September 23
2011
September 26
2011
Vayne VindicatorCircle Vindicator Vayne [S|L] - 50% off
Kassadin Pre-VoidCircle Pre-Void Kassadin [S|L] - 50% off
Lux SorceressCircle Sorceress Lux [S|L] - 50% off
[4]
September 27
2011
September 30
2011
Shen BloodMoonCircle Blood Moon Shen [S|L] - 50% off
Gangplank SpookyCircle Spooky Gangplank [S|L] - 50% off
Rammus MoltenCircle Molten Rammus [S|L] - 50% off
[5]
September 30
2011
October 3
2011
Soraka DryadCircle Dryad Soraka [S|L] - 50% off
Vladimir CountCircle Count Vladimir [S|L] - 50% off
Caitlyn SafariCircle Safari Caitlyn [S|L] - 50% off
LeBlanc PrestigiousCircle Prestigious LeBlanc [S|L] - 50% off
[6]
October 4
2011
October 7
2011
Malphite ShamrockCircle Shamrock Malphite [S|L] - 50% off
Twisted Fate TangoCircle Tango Twisted Fate [S|L] - 50% off
Warwick BigBadCircle Big Bad Warwick [S|L] - 50% off
[7]
October 7
2011
October 10
2011
Lee Sin AcolyteCircle Acolyte Lee Sin [S|L] - 50% off
Irelia NightbladeCircle Nightblade Irelia [S|L] - 50% off
Veigar WhiteMageCircle White Mage Veigar [S|L] - 50% off
Olaf GlacialCircle Glacial Olaf [S|L] - 50% off
Teemo ReconCircle Recon Teemo [S|L] - 50% off
[8]
October 11
2011
October 14
2011
Rumble RumbleintheJungleCircle Rumble in the Jungle [S|L] - 50% off
Blitzcrank BoomBoomCircle Boom Boom Blitzcrank [S|L] - 50% off
Corki HotRodCircle Hot Rod Corki [S|L] - 50% off
[9]
October 14
2011
October 17
2011
Akali BloodMoonCircle Blood Moon Akali [S|L] - 50% off
Urgot ButcherCircle Butcher Urgot [S|L] - 50% off
Miss Fortune WaterlooCircle Waterloo Miss Fortune [S|L] - 50% off
Warwick TundraHunterCircle Tundra Hunter Warwick [S|L] - 50% off
Xin Zhao VisceroCircle Viscero Xin Zhao [S|L] - 50% off
Singed SurferCircle Surfer Singed [S|L] - 50% off
[10]
October 18
2011
October 21
2011
Jax JaximusCircle Jaximus [S|L] - 50% off
Singed HextechCircle Hextech Singed [S|L] - 50% off
Garen DesertTrooperCircle Desert Trooper Garen [S|L] - 50% off
[11]
October 21
2011
October 24
2011
Swain NorthernFrontCircle Northern Front Swain [S|L] - 50% off
Morgana SinfulSucculenceCircle Sinful Succulence Morgana [S|L] - 50% off
Shen FrozenCircle Frozen Shen [S|L] - 50% off
[12]
October 25
2011
October 31
2011
Cho'Gath NightmareCircle Nightmare Cho'Gath [S|L] - 50% off
Karthus GrimReaperCircle Grim Reaper Karthus [S|L] - 50% off
Yorick UndertakerCircle Undertaker Yorick [S|L] - 50% off
[13]
October 28
2011
October 31
2011
Orianna SewnChaosCircle Sewn Chaos Orianna [S|L] - 50% off
Warwick FeralCircle Feral Warwick [S|L] - 50% off
Fiddlesticks SpectralCircle Spectral Fiddlesticks [S|L] - 50% off
[14]
November 1
2011
November 4
2011
Lux CommandoCircle Commando Lux [S|L] - 50% off
Anivia NoxusHunterCircle Noxus Hunter Anivia [S|L] - 50% off
Soraka DivineCircle Divine Soraka [S|L] - 50% off
[15]
November 4
2011
November 7
2011
Miss Fortune RoadWarriorCircle Road Warrior Miss Fortune [S|L] - 50% off
Anivia HextechCircle Hextech Anivia [S|L] - 50% off
Nasus GalacticCircle Galactic Nasus [S|L] - 50% off
[16]
November 8
2011
November 11
2011
Skarner EarthruneCircle Earthrune Skarner [S|L] - 50% off
Nidalee PharaohCircle Pharaoh Nidalee [S|L] - 50% off
Udyr PrimalCircle Primal Udyr [S|L] - 50% off
[17]
November 11
2011
November 7
2011
Twisted Fate HighNoonCircle High Noon Twisted Fate [S|L] - 50% off
Cassiopeia SirenCircle Siren Cassiopeia [S|L] - 50% off
Nasus PharaohCircle Pharaoh Nasus [S|L] - 50% off
[18]
November 15
2011
November 18
2011
Veigar BaronVonCircle Baron Von Veigar [S|L] - 50% off
LeBlanc WickedCircle Wicked LeBlanc [S|L] - 50% off
Olaf ForsakenCircle Forsaken Olaf [S|L] - 50% off
[19]
November 18
2011
November 21
2011
Leona ValkyrieCircle Valkyrie Leona [S|L] - 50% off
Sion WarmongerCircle Warmonger Sion [S|L] - 50% off
Kayle UnmaskedCircle Unmasked Kayle [S|L] - 50% off
[20]
November 22
2011
November 25
2011
Nocturne RavagerCircle Ravager Nocturne [S|L] - 50% off
Kog'Maw CaterpillarCircle Caterpillar Kog'Maw [S|L] - 50% off
Zilean GroovyCircle Groovy Zilean [S|L] - 50% off
[21]
November 25
2011
November 28
2011
The Legacy Skin Project:
Nunu SasquatchCircle Sasquatch Nunu [S|L] - 75% off
Ezreal NottinghamCircle Nottingham Ezreal [S|L] - 75% off
Poppy BlacksmithCircle Blacksmith Poppy [S|L] - 75% off
Evelynn MasqueradeCircle Masquerade Evelynn [S|L] - 75% off
Gragas ScubaCircle Scuba Gragas [S|L] - 75% off
Sivir SpectacularCircle Spectacular Sivir [S|L] - 75% off
Dr. Mundo Mr.MundoverseCircle Mr. Mundoverse [S|L] - 75% off
Dr. Mundo ToxicCircle Toxic Dr. Mundo [S|L] - 75% off
Kennen SwampMasterCircle Swamp Master Kennen [S|L] - 75% off
Sion HextechCircle Hextech Sion [S|L] - 75% off
Shen YellowJacketCircle Yellow Jacket Shen [S|L] - 75% off
Annie RedRidingCircle Red Riding Annie [S|L] - 75% off
Nidalee LeopardCircle Leopard Nidalee [S|L] - 75% off
Mordekaiser DragonKnightCircle Dragon Knight Mordekaiser [S|L] - 75% off
Kog'Maw SonoranCircle Sonoran Kog'Maw [S|L] - 75% off
Twitch KingpinCircle Kingpin Twitch [S|L] - 75% off
Ryze ProfessorCircle Professor Ryze [S|L] - 75% off
Malphite ShamrockCircle Shamrock Malphite [S|L] - 75% off
Tryndamere HighlandCircle Highland Tryndamere [S|L] - 75% of
Amumu PharaohCircle Pharaoh Amumu [S|L] - 75% off
Teemo BadgerCircle Badger Teemo [S|L] - 75% off
[22]

References

Skin Sales Super-Thread by Coreporeal