Adding to @meltysquid Deception suggestion, here are 2 more cheap competitive decks in Mythic:

• Relic War for $12 https://gudecks.com/decks/GU_1_6_BFrBFrKBbKBbKBcKBcKBnKBoKBsKBsKBtKBtKDSKDSCACCACCAZCAZCBCCBCCDCCDCCGJCGJGBJIAYIAYIDdIDoIDo?godPowers=100123&creator=???&userId=1437765&archetype=Big%20Relic%20War

• Amazon Nature for $12 https://gudecks.com/decks/GU_1_5_KBCKBCKBRKBRKBUCAECAECAvCAyCBfCBfCBxCCOCCOCDGCDGCDOCDOCDYCDYCFsCFsCFuCFuCFyCFyCGACGACGBCGB?godPowers=101311,100121&creator=Gomer1n&userId=595887&archetype=Amazon%20Nature

And you can find even more in GUDecks, https://gudecks.com/meta/top-decks - sort by price.