go to your local howdens joinery merchants matey,, they will happily give you some really strong ones which are about 2 meters long and about 7 inches wide so you will be able to bubble wrap all the sections and topkits and put them into just the one tube,, they also come with white plastic end caps!!!!
i go to them all the time for things im selling and they are only to happy to help cos they only throw them out anyway!!
ithink they use them to store wooden plinth strips or something,,but just describe what ive told you and they will know straight away!!!