When I was considering what peripherals to use on my Honeywell 200 project I discounted building a card reader as I couldn't find a card supplier in evidence. There are still vintage computer installations around using cards, so there must be a collective need. It just needs someone altruistic enough to maintain a stockpile at a reasonable price.
Regarding burning through a lot of cards, I am reminded of the story about the company that paid its punch operators by the number of boxes of cards that they drew from stock -- until they discovered that people were taking unused boxes of cards home to supplement their income.
Apart from permanent storage, in an installation using only cards they had to be used for work files as well. I seem to remember that the Honeywell Easycoder A assembler created an intermediate work deck of cards from the source deck, then the final loadable deck from that. That loadable deck was still one-to-one with the original source deck, so a compression program then created a final compressed executable file about a fifth of the size of the original and that was the one actually used to run the program. Considering how many times a program might be reassembled, that added up to a lot of cards only going through the reader once before being scrapped. It's no surprise that a lot of program corrections were patched in on the computer's control panel or manually changed in machine language within the executable decks themselves rather than going to the expense of a reassembly.
Regarding collecting greenbar paper, there was once a panic at our company when it was discovered that the local fish and chip shop was wrapping its product in our old computer listings, including ones possibly containing confidential client information. At the time it was traditional and practical for fish and chips to be wrapped in newspaper to keep it hot, but you couldn't expect people in Tunbridge Wells to eat their fish and chips out of newspaper, could you?
