Every parish I have ever been in has a “holy water font” of some sort (not the little dippy bowls by the door, but, a larger container/dispenser) and people just bring in a container and fill it up.
For Blessed Salt, it would be easy to buy a box of salt and take it to Mass next Sunday. After Mass ask Father to bless it for you. Or, call the office and ask if they have some on hand (I keep a box in my desk in the parish office, have had exactly one person come in and ask for some over many years).