There is no secondary market for Arena, but overall it should be cheaper since you cant pay huge amounts of money for the most powerful cards second-hand
Get out there and Sling some spells

The List Okay, here is the full decklist: Creatures (25) 1 Anger 1 Gorilla Shaman 1 Wall of Roots 1 Urabrask the Hidden 1 Scavenging Ooze 1 Deathrite Shaman 1 Purphoros, God of the Forge 1 Xenagos, God of Revels 1 Eternal Scourge 1 Prowling Serpopard 1 Manglehorn 1 Squee, the Immortal 1 Beast Whisperer 1 Dockside Extortionist 1 Destiny Spinner 1 Radha, Heart of Keld 1 Opposition Agent 1 Kediss, Emberclaw Familiar 1 Prosperous Innkeeper 1 Chatterfang, Squirrel General 1 Aeve, Progenitor Ooze 1 Ignoble Hierarch 1 Timeless Witness 1 Goblin Anarchomancer 1 Devilish Valet Planeswalkers (1) Lands (40) 1 Strip Mine 2 Forest 1 Wooded Foothills 1 Gaea's Cradle 1 Wasteland 1 Reflecting Pool 2 Swamp 2 Mountain 1 Taiga 1 Bayou 1 Badlands 1 Shizo, Death's Storehouse 1 Overgrown Tomb 1 Stomping Ground 1 Blood Crypt 1 Graven Cairns 1 Fire-Lit Thicket 1 Jund Panorama 1 Savage Lands 1 Exotic Orchard 1 Dragonskull Summit 1 Rootbound Crag 1 Verdant Catacombs 1 Lavaclaw Reaches 1 Raging Ravine 1 Command Tower 1 Woodland Cemetery 1 Kessig Wolf Run 1 Cavern of Souls 1 Temple of Abandon 1 Opal Palace 1 Temple of Malice 1 Command Beacon 1 Luxury Suite 1 Spire Garden 1 Undergrowth Stadium 1 Ziatora's Proving Ground Spells (33) 1 Rancor 1 Vampiric Tutor 1 Mana Vault 1 Sol Ring 1 Demonic Tutor 1 Mana Crypt 1 Food Chain 1 Berserk 1 Terminate 1 Skullclamp 1 Greater Good 1 Krosan Grip 1 Harmonize 1 Beastmaster Ascension 1 Nihil Spellbomb 1 Go for the Throat 1 Beast Within 1 Tragic Slip 1 Vandalblast 1 Cryptolith Rite 1 Heroic Intervention 1 Skull Storm 1 Genesis Storm 1 Rhythm of the Wild 1 Cindervines 1 Force of Vigor 1 Veil of Summer 1 Arcane Signet 1 Embercleave 1 Plumb the Forbidden 1 Stinging Study 1 Tamiyo's Safekeeping 1 Blood for the Blood God

They enable combos, heal Pokmon or get players the cards they need to beat their opponent
Once you do obtain the cards you want, though, you have to follow certain strategies to win often