It’s not hard to find alcohol in Spain as you can buy it pretty much anywhere – in restaurants, bars, supermarkets, etc.
In Barcelona, alcohol can only be bought until 11 p.m. After that sale in supermarkets and minimarkets is prohibited.
A glass of wine or beer at a café/ restaurant will be about 2-2.50 EUR. A small, local brand beer in a bar can also be found for 1-1.50 EUR but if you decide to buy a bottle of domestic beer (0.5ml) at the market you will pay about 0.80-0.90 EUR.
A standard red table wine can be found at price range between 1 and 3 EUR, but an average price for good wine is 4.50-6 EUR.
A bottle of vodka at the store would be around 15 EUR, and for a single cocktail at a bar be prepared to pay 10-14 EUR.