Britman, if you have a bit of hosting, then you can stick your pics on there and link them into ebay for no extra costs and no limit of the amount you can post - apart from your hosting costs etc. but if you already have that, then it's not an extra cost.
Using a box is great - storing it is a bit of a pain, of cours an alternative use for the box is to stick it over a flash and you have a softbox - great for portraits of your loved ones

Granty, I know what you mean about that, I've had people check with me that it is the actual item, even though the serial number is visible, and listing contains the serial number and the fact that it says 'photos of actual item' but ti's always worth checking!
Just having a quick look on there, and 50cm lightboxes are going for about £11 and 80cm ones for about £15 - they fold flat for storage too - might be worth it for anyone listing a lot of stuff regularly, just work out - as britters says - how to adjust your white balance!