Cheap place to go on holiday, young couple?

hi, me and my girlfriend are looking for a cheap beach holiday, don't want anywhere that uses the euro. We would like to be close to nightlife, and a beach, however, we don't want to go somewhere that is overcrowded with groups. We were thinking of sunny beach in bulgaria. We would like to know if there are lots of groups or if there's not that many, if anyone has any other suggestions we would be grateful, thanks