If a seller expects me to arrange the courier, or to pay for it, I don't even consider buying from them.
All basses I sell include postage and packing in the price. I've sold and sent basses on here to as far away as Australia and Canada, one was a Warwick Streamer 6 and the other was a Vigier 5. It must be considered that some couriers only let you insure up to a certain value, if that's the case then I let the buyer know to make sure they are cool with it.
I've sometimes sent basses UK mainland in a case and bubble wrapped, which has been fine. But I much prefer to meet up or deliver if I can. It makes it more easy because I travel a lot with work.
At present I'm buying 2 in and 1 out. One's going to Scotland in it's case and a box and I'm picking one up on my way to London on Thursday. The last one is coming from Scotland and as I've done business with the guy before I know it will be well packed.
Would you believe I once bought a £1200 bass from a guy and when I opened the case there were no bloody strings on it.
It beggers belief sometimes.