I've found that the accuminata can be stubborn with bloom. Mine is, anyway.

The seller 'dogwoodritter' has them for sale now on ebay. I have been searching for one for awhile and finally found it. Not sure how well it'll do down here on the gulf coast, but maybe it'll be okay if I put it in partial shade.

M. acuminata is a fine native species, but would, I think, be marginally hardy in your climate zone. Dry alkaline soil would not be ideal, either. This species takes many years to bloom and then the flowers are not terribly noticeable because they appear after the leaves, are usually high up, and the yellow-green color does not stand out.

You would probably be better off with a cultivar listed as Z4 hardy. Fairweather Gardens and Rarefind Nursery have good selections available by mailorder. There are no doubt other nurseries as well. I would not buy anything on Ebay that does not indicate that it has been inspected by the relevant state agriculture department.

Last year I found a source for a couple seedlings. Unfortunately, I ordered them too late. They looked like they were kept in cold storage, they produced buds earlier in the spring while in storage, they weren't planted by the seller, and the buds died while in storage. The stems and roots seemed OK so I planted them. I tried to contact a person at the website about this but received no reply. Maybe this spring they will come to life.

Seedlings will need many years to reach flowering size. And these flowers may not show up much. Would be better to buy grafts or cuttings of a named clonal cultivar known to produce appealing flowers.

As long as they are kept watered and winters are not too cold for the particular kind planted it is possible to grow deciduous magnolias in dry western climates.

I'm not concerned about the flowers but I agree that other people viewing the trees might appreciate the flowers. Also, might've been better if I bought larger plants. Seedlings of trees in climates that are a bit harsh for the trees don't grow very fast if any. I have the Magnolia seedlings in pots in a sheltered place for the winter.