Alcoholic beverages are notoriously expensive in Singapore because their listed prices have to factor in the customs duties payable on alcohol. Even beer and spritzers with low alcohol content are dutiable. When you have drinks in restaurants and bars, the menu price is further subject to 10% service charge and 7% Goods & Services Tax (GST), so you can expect to pay at least SGD10++ (about USD8) for a beer in Singapore. The beer stocked in your hotel's mini bar is also in this price range - exempted from the service charge since you pull out the ring-tab of the can yourself, but still subject to 7% GST. So, do remember to take advantage of your duty-free 'beer allowance' at the Airport duty-free shops when you arrive. Even this duty-free 'beer allowance' is a modest 1 litre which is equivalent to 3 x 330ml cans of beer sold in a bundle at SGD6.00 - SGD9.00 (depending on brand).  In addition, you are entitled to buy up to 1litre each of hard liquor and wine. If you live in a downtown hotel and  wish to stock your own supplies in your mini bar, Carrefour Supermarket at Suntec City (subway station under construction) and Plaza Singapura (subway station: Dhoby Ghaut) has reasonably priced (by Singapore standards) house-brand and European brand beers and wines.

Having said that, there are ways to have your booze in style and on the cheap in Singapore. The New Asia Bar on levels 71&72 (take the elevator to level 70 and climb the flight of steps) of the Swissotel The Stamford (subway station: City Hall) has happy hours from 5.00pm thru 9.00pm daily with 1-for-1 drinks. Get a window seat or perch yourself on one of the high bar stools for a terrific view of the civic district and financial district at dusk.  If you are female, many watering holes have Ladies Nights on Tuesdays or Wednesdays, when you can have free flow of housepours and standard drinks for free or at half price.  Cheers.