I find the idea of posting stuff off a bit alarming – if you've got a bit of old ratner you want to cash in and take it to a shop, they can make you and offer for it and you can decide on spot whether the offer is good enough or not, if its not a good enough offer – walk away. With these Ann Diamond endorsed adverts you post of your stuff and they send you a cheque – but for how much? £1000? 30p? Doesn't matter seemingly, you'll just get what you're given and the deal is done.
Compared to pawnbrokers/cash converters who do at least make a fairly concerted effort to ensure that the goods they are offered are legit, its a pretty flimsy transaction, they've obviously got no qualms about how hot the stuff they are sent might be.
Anyway, I've got a new business idea. Post me you bike and by return of post I'll send you a cheque for any amount that I see fit