Decent box – maybe even a LCD/plasma tv box from the cardboard dump at the tip would do.
Frame protection – bought 100m of bubblewrap off eBay for something daft like a fiver – that’s kept me for a while, and as a bonus if I ever get stressed I can cut off a metre of the stuff and just pop it all….
Parcelforce tends to be my preferred courier just ‘cos I iz lazy and it’s round the corner. £14.25ish for a frame (it’ll never go over the weight limit).
Depends on price of frame and the risk you take but the insurance ramps up fairly quickly. You’ll get the basic £50 or whatever back if it goes missing or broken if you don’t so up to you and you’re risk management on that one.