Zantac is a class B drug, meaning that while it hasn't been proven safe, it is believed to be safe. Zantac is only for heartburn though- while it can relieve NV from that- Zofran works completely differently, so I'd be a little leary of using JUST Zantac instead of Zofran. I used Zantac during two pregnancies, no harm to my 3 babies. However I will say, during my last pregnancy it stopped being very effective in my 3rd trimester, and I wish I would have tried an PPI instead.
Other things you can try is Unisom/B6 combo (Bendectin). Perhaps they will cover Anzemet or Kytril? Those are "sister" drugs to Zofran, they are also both still pretty expensive. There is also Tigan, Compazine, or Meclizine or Dramamine. I actually did find Meclizine helpful- I took it mainly at night. Helped me get a better night's sleep & on those days I felt less nauseated & vomited less & ate/drank more. There's also Reglan too.
Check out the list of medications page for more info.
http://www.helpher.org/hyperemesis-grav ... ations.php