For organising your office/stockroom, can I suggest looking at Really Useful Boxes ? They are good and sturdy, strong enough to stack nicely right up to ceiling height, and the lids clip on firmly.

I use a bit of brown tape and Sharpies to label each one. You can give each box a number then build that number into your eBay Custom label field. Having a spreadsheet telling you what's in each box and whether it's listed, ready to sell, or needs prep work will make everything massively more organised and tidy. But narrow down to just 2 or 3 sizes of box, ideally ones which will mutually stack (e.g. a deep and shallow one of the same footprint).