It's around 3 leva for a low quality popular Bulgarian beer like Kamenitza or Zagorka, personally I do not like both of them because of the headache after use. Better go for a better quality beer, or even any imported ones, prices are around 5-6 leva.
never found any problems with the local beers which range in prices, mind you i will have a headache after to many of any type of beers. Oh well not long before the headaches start