Zambia has indeed got expensive, a far cry from 3 years ago where it was easy to get a free visa wavier and some good deals on hotels. It still isnt as bad as some places though (Russia and Venezuela spring to mind as having crazy visa fees and departure taxes).
There is a pretty good backpacker network through Zambia to Tanzania and Malawi and there is the luxury tour mega expensive fly-in service at the other end of the scale and not a whole lot inbetween. The best deals I found in Livingstone were the private rooms or cabins in the hostels, just as good as the hotel rooms, or better in many cases. I cant remember the names of the places I have stayed in but no doubt they will have changed a lot since then anyway. Some packages with hotel and activites would arrange private mini-bus transfers to and from Lusaka which were way cheaper than a flight but a lot more comfortable than the bus.

Potfish, November can be quite nice (I am going to Southern Tanzania in Nov this year!), depends on what you are planning to do and a bit on how early the rains start. Many camps will start to pack up in early Nov in the more remote areas. However the prices tend to fall sharply too. April/May is a bit early for the more wilderness camps too as they are still setting up after the rains. June however would be great as camps will be open but not peak season yet so cheaper too, water would be high at the falls then too.