Peruvian Airlines flies from Arequipa to Tacna 5 times a week. Alternatively, Flores Hermanos operates a bus from Arequipa to Tacna hourly. Tickets cost $9 - $24 and the journey takes 6 h. 2 other operators also service this route.
From Arequipa taxi to Arequipa airport, fly to Tacna airport, then taxi to Tacna. 1 h 3 min $267. From Arequipa bus to Tacna. 6 h $18. From Arequipa bus to Moquegua, walk to Moquegua, then bus to Tacna. 6 h 6 min $59. From Arequipa taxi to Tacna. 5 h 16 min $106. From Arequipa drive to Tacna. 5 h 16 min $41.
Yes, there is a direct bus departing from Arequipa and arriving at Tacna. Services depart hourly, and operate every day. The journey takes approximately 6 hours.