Hello, I just bought one yesterday at A & P Nursery on Baseline one block east of the 101. They had several left after I bought mine. Their phone number is 480-839-5362.

Ps I've found A & P to have the best prices around.

Having dealt with bind weed, I'd be afraid to plant morning glories. I even have some sweet potatoes, which are related to morning glories, that I can't get rid of.
Morning glories can be very invasive.

It's in the same family, but it's not as invasive as "common" morning glories (not in the same genus either).

It's a good plant for the desert if you don't over-water it (though it's not exactly low-water use, it doesn't handle having wet roots for a long time vs. dry soil).

Convolvulus is a genus in the bindweed family... kinda scary. But I would assume it was allowed since they are selling it. But then again, assuming can get ya into trouble sometimes...