I don't think the alstromeria's are evergreen, but I'm not positive. I had one in a pot under the roof overhang and it held on to it's leaves last year, but went dormant this winter.
I have a couple of rooted pieces of the species, and so far, they have held on to their leaves.
Which plumbago are you looking for? I have P. Auriculata, if you'd like some rooted pieces. I'd love to trade it or something else for variagated alstromeria.
I haven't seen it offered locally. And you're right about it being the attention getter. It's got mine.