Buddleia are pretty hardy plants. If you manage to get enough root and keep the roots damp (if they don't have much soil on them then a few soggy tissues wrapped round and then a carrier bag to stop it making a dribbly mess everywhere will do the trick for a while until you get to transplant them). Prune them back a bit when you pop them in the soil and bobs your uncle.
I'd be inclined to rip off a few branches and bung them in the soil in a shady place as speckled wood suggested just in case the main plants don't make it.
Good luck!
