“P&P” postage and PACKING...the latter being a very convenient way of boosting profits ?
I only ever charge the actual cost. As a small business I just couldn't bring myself to over charge people for postage. Ive even part refunded postage after initially over charging !
Richard, when I see over priced postage I just go elsewhere. Im not sure its ever encouraged me to fill a basket. I will pay over priced postage only if its something I really need or want and cant get elsewhere
Horses for courses. We all do thing differently and in the end its the punters choice where to spend their cash.

EDIT: to be fair, most of the stuff I post is all the same size package ( and roughly the same weight ) so its easy for me to have fixed prices on the majority of my post out. I can see it getting tricky when different weights, sizes and product values come into it.