I know, but I want to use either padded bags or rigid mailers to protect my stuff and help ensure it doesn't go through the letter sorting machines (not all of my items are fragile, but some are bendy and I want to keep them straight, some are much better presented in boxes, and others are kept under 2cm by not being given the chance to bunch up in a flexible envelope), so I don't really feel it's worth me personally keeping another postage / packaging option on hand for the once every so often I have an item that can be put in one.
Plus paper envelopes aren't supposed to contain non-flexible things, and if memory serves the pre-paids are paper envelopes?
I'll follow these AP guidelines, and use priority on them all. I / we (and by we I mean myself and my buyers), do pay a bit more, but overall I think it's worth it (as much as I distrust AP, and think a lot of their prices are pure gouging, I also know their MO and if a little extra here and there means letter prices don't see another dramatic increase so soon after the last one, then all the better. I guess I see it as kinda paying protection money, even though there's the ever present threat they'll send someone 'round to "convince" me why I need protection, and while I'm lamenting my kneecaps, they jack up the price cause now they have to protect me from the goons they sent in the first place....or something like that, it sounded like a better analogy when I started, and then just went off somewhere and I couldn't stop it 
).
