They have everything you need at that shop. Botanicare Pure Blend Pro, House and Garden A & B, Sensi Bloom A & B. General Hydroponics FloraNova, etc... Just get the base nutrients of any of those or another and don't get talked into buying a bunch of additives. Any of those will work.
But don't expect miracles with that plant even if you start feeding it properly. But for your next grow you'll have what you need to feed the plant properly from seed to harvest.
Good luck.