We ALWAYS stock up at Duty Free on our way back to Ecuador. You can each buy 3 liters. We usually buy good vodka, rum, scotch, and other good spirits.
As for wine, a lot of the expats here drink box wine. It’s somewhere around $4 or $5 a box. They say they like it. I can’t tolerate it. We have a local boutique store here in Cotacachi where I can buy decent wines for $8 to $10. It’s an expensive habit, for sure, but life is for living! 🙂
This may be too late, but there is a big liquor store on the same street as the Holiday Inn Hotel in Quito (street may be Orellana, I can’t remember.) They have a great selection in there.