From Sofia to Burgas you can get:

1. Flight domestic Sofia - Burgas, the cost of about 50 EUR per ticket for 1 person, the schedule of flights is on the website of Bulgaria Airlines, flight time is 1 hour.

2. Bus Sofia - Burgas (goes from the bus station in Sofia), the ticket price is about 20 EUR. The timetable is on the website of the bus station in Sofia. Travel time 6 hours.

3. Taxis, at a cost - about 100 EUR to Bourgas in one direction, but most likely the taxi driver will have to pay round trip, that is 200 EUR. Travel time 5-6 hours.

4. Hitchhiking - for free, travel time is not less than 6 hours.