I have too much stuff, and I would like to get rid of it. (OK, some of it – I am not quite at the point where I believe you can have too many DVDs or board games.)

One of the main places I do that is Amazon. The absence of a deadline means that you can wait for buyer who wants it for £x rather than having to settle for one who wants it now, but for less. (It's possible they'd pay more if there's a bidding war, but you can't guarantee that.)

The problem is that if you want to sell a Microsoft keyboard on Amazon, you can't. Unless you jump through several hurdles, for example by showing invoices from an authorised distributor. This applies to everything and anything they made, hardware as well as software.

If you want to sell a Sony Walkman on Amazon, you can't. You're told "You are not approved to list in this product category and we are currently not accepting applications." This applies to everything and anything they made: games consoles, cameras, TVs, etc etc etc. Some companies can sell them, I can't.

In both cases, you could do so a while ago – I've sold both there – but you can't any more. There are doubtless other brands in this situation.

I understand why Microsoft and/or Amazon want to stop people selling, for example, Windows licenses without being sure they're genuine. But keyboards?? And what's the issue with Sony?

The effect is that consumers cannot sell their unwanted gear there, losing one large marketplace (and one that is, or was, nicer to sell on than eBay) and we pay higher prices for products by these companies because the supply is being kept low.

In addition, you only find out this is the case when you try to list a Microsoft or Sony product, because there's no indication on Amazon to buyers that the supply has been artificially restricted.