Normally, plastic bags (specially for food) are printed before they are actually bags.
The roll of plastic is printed for example on flexography, and the roll of plastic (sometimes called a sleeve) is converted into a bag. You can add optical markers on the print, so the next machine understand where the cutting and sealing must be.
The ammount of minimum bags is considerable, because you could be charged for X ammount of kilos or rolls of plastic printed, regardless the size of the bag.
As this is a small bag, you have much more than if you have larger ones. Probably tenths of thousands.
Silk print could be used. But I do not think it is a good idea. It is a manual process, and the plastic is not the most noble substrate, because it could stick to the screen. Probably some small information at one color only.
And as mentioned, this method could be not safe to insert food on the bags.
Some inks for plastic are solvent based, that dry by evaporation or oxidation, which means they can smell and have some slight toxic vapors.
And some other inks (solvents) could react to the plastic, or penetrate it.
Stickers are not a bad idea at all. You could think of printing on a transparent substrate perhaphs.