Wizz Air and Austrian Airlines fly from Sofia to Budapest once daily. Alternatively, EAAA operates a bus from Sofia to Budapest once daily. Tickets cost $30 - $50 and the journey takes 11 h 41 min. Tourbus Bulgaria also services this route once a week.
How to get from Sofia to Budapest
From Tzarigradsko shose Blvd. line 84 bus to Sofia airport, fly to Budapest airport, then bus to Budapest. 4 h 54 min $74. From Sofia bus to Budapest. 11 h 41 min $52. From Sofia Serdika bus to Népliget M then bus to Deák Ferenc tér M. 12 h 19 min $1. From Sofia drive to Budapest. 8 h 8 min $104.