It all depends. Half a gram of Phenidone, 10 grams of hydroquinone and 1/2 cup of sulfite make a gallon of a pretty good developer for film with a fair capacity which I always thought was due to the excess of Q and the relative insensitivity to bromide build up.
Nowadays, I would substitute sodium ascorbate for the Q and leave out the sulfite, restoring the pH by adding some borax.
I figured out that 4 liters of a PQS working solution could cost as much as $20. 25 liters of HC110P working solution that I tested would cost about $16. I know that amount would develop 50 standard rolls of film.