How many times do you see items that you would like to bid on listed as "Collection Only" because they are too big, too heavy, too large or too bulky (according to the seller, that is) to post?
As a seller, how often do you sell items at a price that is well below what similar items have sold for because you feel you are unable to post?
There is always a way to ensure you maximise your final cost, and provide P and P that is cost effective to both you and the buyer. The Post Office are so expensive these days, that they have almost ruled themselves out of the parcel delivery business, especially when there are so many low cost alternatives.
Most couriers will offer a collection service - from your door! You can book on-line, pay via Paypal, print out the required labels then sit back and wait for the courier to arrive. Yes, there are drawbacks. You have to be at home all day (although some will offer a "safe place" collection service) - or at least until the courier collects the parcel. The convenience, however, will often outweigh the drawbacks.
Hermes (the courier) for instance, will carry items up to 15kgs. Any heavier, and you will need to split the parcel, and make up two. The cost, however, is very good.
Parcel2go are well worth considering. Link your e-bay account to them, and when an item ends (and is paid for) you can log into your account with p2g, and decide which courier to use, which service, and the cost.
I have used both services for some time now, never had a problem, a lost parcel or one that did not arrive on time.