It would be better to use 1.5" even though it isn't for a long run (of plumbing). Mag pumps work better when you double the thread size. A mag 9.5 or 12 has 3/4" threads, so doubling it would be 1.5" plumbing.
SpaFlex is sold online or at Home Depot / Lowes. They sell it by the foot. I have pictures of all my plumbing using SpaFlex as well as rigid PVC on my 280g's sump page. And one day I'm going to make the time to do a page about plumbing because all I do is type this stuff out all the time. I'd rather just do it once, do it right and point people to it from now on.
I do have a couple of pages showing plumbing, both to my own sump as well as the "How to install a sump in an existing setup" page.