long shot, but any chance you know a way to find short term rentals in the city center? I currently live in Lozenets and while I love it I’d prefer something more central like say Rakovski street
Speaking of Lozenets - it has one of the best wine shops in Bulgaria. And it is definitely a Big Plus. Actually, I have summer office in Sozopol and it works OK, just you will need to be prepared of VIVACOM 24-48hrs downtime once or twice per season. Otherwise OK. Business wise, Bulgaria for a foreigner is very good, banking is OK.
The only thing i can think of is AirBNB, but from what i've seen as prices there, it can be x2-3 more expensive per month, but also depends on your use case. Also try the more larger rental/property agencies like Mirela and Address, they might have few short-term apt.