The best bet is to hunt and peck for things to save. Though it takes considerable thought, one way to keep your composure is to timetable.
Start with your geography. Is there fresh water about year ‘round? If not, it would be good to stock up a few water filters, because there is generally non-potable water that could be made fresh. And because people must have fresh water, if there is none, they’ll put all their resources into getting it. So shortages can’t last too long, or most people will have to scram.
So using this type logic, figure out what you must have, and for how long, of each particular thing. You’ll probably discover that a lot of what you were planning to save is not really needed, at least in the quantity you were thinking. And saving up too much just means you’ll have to throw it out.
We stock up on things we constantly use, and rotate it. If it has a shelf life of 12 months, then we do not buy a 24 month supply. For most things, we get them on sale.
We have a well, and we do have some water filters, but they are not totally necessary, hence we don't have a lot. We have been exploring how to get water from the well in case of a long time shut down of electricity.
We also have a creek on our other property, instructions for converting such to safe drinkable water. We have rain barrels that could be used to haul water etc etc-I won't bother you with further details.
But anyway I do think it is important for everyone to sit down and think what if all modern technology was gone overnight or too expensive for you to buy. How would you survive independently? Focus on food, water, shelter, meds, protection, and hygiene(not necessarily in that order).