Clothing gets taxed to the max. Expect to pay high amounts on these, anything from 50 to 100% tax before import duties which is a fixed cost.
Yes. One can get an idea of the cost by checking it out via Amazon global shipping as that will give you the tax.
Clothing is one of those categories, they want you to rather support local manufacturers.
Selection in SA sucks though and it's not as if the clothing is even made in the country it will be sent from.
For example try to get anything as comfortable as Ecco shoes in SA? Nope.