Autocannons are not particularly expensive, when compared with their own targeting systems, and especially when compared with direct energy weapons of similar range and effectiveness. Heavy machine guns are even cheaper (albeit with diminished range), and medium (7.62-mm) MGs are cheaper still.
The link refers to heavy field howitzers which are actually quite costly, although their barrels are not.
Autocannons are not particularly expensive, when compared with their own targeting systems, and especially when compared with direct energy weapons of similar range and effectiveness. Heavy machine guns are even cheaper (albeit with diminished range), and medium (7.62-mm) MGs are cheaper still.
The link refers to heavy field howitzers which are actually quite costly, although their barrels are not.