Another thing, when you sell to the recyclers, you send the bare phone. When you sell on eBay, you have to sell with box, charger, cable, headphones, etc. A new charger and cable are £30 (£15 each I think), and I can never have enough chargers and cables (although obviously the 5 onwards requires the new cable, making the old cables useless).
On eBay, completed listings for a 64GB iPhone 5 are selling for between £350 and £400, so let's use the average of £375, minus the 10% eBay fee is £337.50, minus Paypal fees (? no idea how much, and by the way, who I hate with a white-hot heat). Minus the use of the charger and cable (let's say £20) and we're down to £317.50 (without taking anything off for Paypal). So ok, I agree it is still more than what the recyclers will pay, but this is assuming you are lucky and get a good price, you don't have any timewasters (let alone someone who is out to scam you -- e.g. buy the item, and then instantly place a claim, freezing your funds, etc). For £50 (in the case of the 64GB 5 which is obviously at the top of the heap), and much less for lesser models, selling direct is just not worth the hassle, in my opinion.
I wish there were recyclers for other things like computers (I have too many lying around the house because I can't steel myself to deal with the countless a-holes that are on eBay).