Well here goes,
Looks like the D3004/66000 if you take 20 will be +- R1300.00 each all inclusive, so total for tweets about R2600.00
The 18w/8531-00 will be about the same at R1369.00 each so x 2 for the ZRT = R2738
Total ZRT = R5338.00
Total ZRT 2,5 = R8076.00
Regards,
Stu