The Republic of Botswana is a member of the SACU (South African Customs Union), therefore, the parcels sending  between the countries-member of the union are not subject to taxes or duties.

FOB - The valuation method used by Customs.
FOB = the declared value of the goods. The cost of delivery and insurance is not taken into account.

Customs duty
From 0 to 45% of the FOB amount. With an average value of 28.74%.

Sales tax (VAT)
12% of the CIF amount (parcel cost + insurance + shipping cost) and customs duties.

Threshold for duty-free importation
There is no minimum threshold. All incoming parcels are subject to duties and taxes.