Check the price of the Vic Falls Hotel before you write it off. Can't imagine it will run to $600 (although Zim has differential pricing in 3 tiers: locals, South Africans and Ladies in Cal ). And it is a gem with proximity to the falls meaning you can experience them at all hours of the day.

You might try booking it direct or through an SA agency? Frankly given the desperate state that poor country is in, they need every booking they can get so I can't see them being unwilling to negotiate.