Hi Con,

The picture looks like Datura to me. It is not a vine but a low growing shrub. It grows about 2-3 feet high, gets very bushy and does bloom profusely at night. Three dollars for 10 seeds sounds like a lot of money to me. I have lots of seeds and I will be happy to send you some if you send me a SASE. I collect stamps so an envelope with a cancelled stamp form New Zealand would be great. Email me and let me know if you want the seeds.

Suz

I'd say it's the vine, not the Datura. The flowers lack the hooks typical of Daturas. Also, Datura blooms are longer, deeper-throated than Ipomoeas.
Yes, I'd say regardless of what it is, the seeds are way overpriced!