Charity shops are good. I often frequent them and have bought some amazing stuff, but they need to pay rent, rates (presumably reduced), utility bills and the like. They also tend to contain a random array of stuff which needs to be sorted through and have to close when there aren't enough volunteers,
so they can't be open twenty-four/seven.
Another set of establishments is the minimally staffed video/video game rental shop which is essentially a heavily armoured vending machine situated in a small shelter accessed by membership cards which can also carry credit, topped up when required and accessible at all times.
I propose a combination of the two, thus.
Barcoded goods received of a standard size, such as CDs, DVDs, VHS and audio tapes and books, as well as tagged new garments, are scanned and identified. Where possible, the items are deposited in the machine by the public. The information is recorded both locally and on an online database and the products are stored in local vending machines in small premises. Customers are issued with swipe cards which can be topped up with credit. They can use these to access the premises, pay for goods in the vending machines, or online via a serial number and password to search for and pay for goods nationwide, or maybe even globally, which are automatically packaged, addressed, stamped and dispensed, then posted to them. The cards can also be used free of charge to access capsule accommodation on the actual premises, providing overnight sleeping and toilet facilities and food for the homeless. These capsules collapse when vacant and only become available when the swipe card is used to access them for security and space-saving purposes. The main part of the premises is monitored by CCTV without blind spots.
This would enable charities to operate with fewer overheads, provide minimal accommodation for the homeless, and increase the value of charity stock by providing people with specific desirable items. No cash is involved, reducing the risk of vandalism or mugging.
There would still be some items which could not be fitted into this system, but charities participating in this system would also be able to save money by renting smaller shops for which less labour was needed, while still providing the opportunity for volunteers to gain work experience and just generally volunteer.
Incidentally, if there are unforseen adverse consequences to the accommodation side of the idea, such as cost or safety, i'd be happy to drop it and stick with the rest.
The machines themselves are, to a considerable extent, made out of the likes of old VCRs, CD changers, computers and TVs, so it's also reuse of obsolete equipment.