PPP is fundamentally flawed when it comes to comparing overall living standards between countries but it is rather precise if you want to compare costs.
Utilities, materials, labor and taxes in Russia are nowhere near that of Australia. You can expect their plane to be a bigger bang for a buck.
Yet Russia has a hard time of providing the reliability, advanced technology, and close tolerances needed for top notch weapons systems today. They lack the financial and technical resources because their economic base is too small for the task. To support their great power aspirations, the Russians thus resort to touting prototypes and announcing programs that will never enter production. The Russian arms industry is in decline and is of diminishing consequence in international markets. Russian weapons today may be cheap but they are, with limited exceptions, obsolete and inferior.