Ur budget for 250-400 including installation or not? Do u want new speakers or used? Do you want spl speakers or sq speaker or speakers which moderate in everything etc? If you give enough information then the sifus here can recommend something suitable for you.

Few years ago, my friend who does not have any electrical knowledge wiring his HU and in few days when he driving smoke come out and soon very fast the car was on fire and total loss. If ur not sure or facing problems better bring to someone who is knowledgeable. Better use abit of money now rather then possibility of losing alot of money later on.

Try changing the rca to see if got any differences.If no spare rca borrow from friend la.