You're best chance on this Eucalypt would be at Kuranga Nursery in Mt Evelyn. The advertise having Eucalyptus (Corymbia)ficifolia Grafted Red-flowering Gum so assume they'd have the one you want.
I have a summer red growing in a large half wine barrel - it does OK but doesn't flower as well as ones in the ground. I find they are somewhat erratic flowerers (in Adelaide, anyway).
We have the Summer Beauty (salmon coloured flower) in our back garden. I see absolutely no reason why they couldn't be grown successfully in a pot. However, I would plant it out into a fairly large/deep pot and ensure it's out in the yard somewhere where it'll get sun. Cost-wise you're probably looking at around the $45 mark. That's not a huge cost considering they're grafted.
