The nurseries I buy them from grow them only from seed.

PansySoup, Sounds like your Michelia is thriving - and I'd like to know how you have accomplished this happy condition. I live in South Bay area (south of San Jose) in Sunset zone 16, though we are close to the Santa Cruz Mountains and get some moderating ocean influence. I recently bought two Champacas and four rather scruffy Figos (good deal on sale) and am trying to figure out best location in our 1/2 acre landscape. I plan to separate the two types so fragrances don't conflict. I have areas facing East along enclosed entry patio wall (full morning sun gives way to shade after about 1 pm) but fear the wall may be too hot, and concern that I must prune champacas so they don't run into eaves... Also have long North facing fence in side yard (outside bedroom windows) with some dappled shade of very huge old oak, where I am considering placing the figos... might consider container planting to preserve options until I can see where they are happiest; I also wonder about pruning them into broader, shrubbier shape (the champacas are already about 5' tall and narrow; I want to coax them into broader form... the figos are all rather scruffy and leafless, rather leggy - can I just whack them back to 2' or 3' stubs to encourage bushiness?)
I'd appreciate having advice from experienced, successful michelia cultivators regarding my plant renovation goals - I don't want to do anything that is radically contrary to the natural habit of the plants. Thanks in advance to anyone who cares to reply. I am really looking forward to the famous fragrances of champaca and figo!

Michelia Alba Page from HK Education Department

Click on the fruit icon and it mentions that M. alba doesn't fruit while M champaca does. And it gives ya a nice photo of M. champaca fruit developing.

And the page also has a photo of a large (9m tall) M. alba and some information on growing preferences.

I'm happy since I bought mine about 2 months ago for about a buck and a quarter US and today I just cut my first flowers. mmmmmmm...

2 buck and quarter. That would be an incredible bargain here for an M. alba. It's 10 to 15 times the price here. Airlayering is done on the harder to propagate M. alba, so you should be able to do it with M. champaca. Your get a plant that will definitely flower much sooner for you. M. alba is one of the few non fruit producing trees I would plant!