Other than Big 4 schools in Lusaka?

Dear Expat.com friends,

I'm considering a move to Zambia-Lusaka and schooling of my children is one of the biggest considerations. I've found on this forum and elsewhere 4 major names: AISL, LICS, ISL,  and Baobab. While the American one is out of question, even the other three have quite steep fee and would strain my finances quite a bit. I'm joining a company in development sector and the package would be a constraint.  What I want to know that if there're any other good schools which offer international curriculum and have more affordable fees? I've seen names like Lake Road PTA, Woodford and Rhodes Park and their fee looks lower. How would you rate these schools? Are these mostly patronized by locals only or can one expect some Expats' kids in these schools? Apart from these, any other school that you find suitable, please recommend. Even a school that's upto priamry only is ok for now. My children are in grade 4 (girl) and 2 (boy) and would go on to 5 and 3 resp. coming August. Currently they're in ICSE board in Mumbai (India).

Actually my decision to move depends on availability of good schooling option in my budget i.e. about 5000-6,000 USD/child max.

Thank You
-Siddharth