I would book right now if your dates are fixed already!

Air Berlinīs 2010 summer schedule flights are bookable already !
Do not expect any special offers for that (fares are low anyway right now).
Fares are simply capacity controlled so the later you book the more people will haver taken the "cheap seats".

Air Berlinīs lowest one-way is a Promo Fare of 29,-EUR all-in (= 6,-EUR +tax but no service charge will be charged !!!)
Any fare higher than 6,-EUR will attract an additional ticketing service charge besides the taxes !
Just checked randomly for june 2010 and most Tickets were 44,- or 55,-EUR incl. tax and service charge ...

AB is the only airline offering non-stop flights between Salzburg and Berlin.
Next to this there will definetely be no other airline beating Air Berlin by price or service quality between both places !!!
Air Berlin even serves free soft drinks and a small snack on every flight (free newspapers/magazines are availlable sometimes albeit usually in German)

If you need more info PM me !