-
Assuming you value someone's time at London minimum wage, and they can do all the deliveries in a single hour, you'd need at least 5 orders combined to cover the cost in saved postage, and being realistic you're not going to be able to sort/deliver them in under an hour.
Its similar to the idea about driving to get cheaper petrol. By the time you factor in the value of your time going to wherever it is you are better off just sucking up and paying for the difference
It's difficult to judge the actual cost of postage and labour involved in picking and packing small orders. I can accept that it's not negligible, but I can't believe that it's the same for the two items I mentioned. With their current system it just feels like someone buying a single bolt is subsidising other larger orders. If that's what it takes for them to keep going then I'm not going to quibble; they provide a very valuable service, but they're not a charity.
I still think it's a reasonable idea to club together to get small items posted together though.