I wouldn't pay that for them. Should be a relatively straight forward install. Have just ordered some off AliExpress, price with Tax was under £80. Will feedback once I've received and installed them.
Agree with others that these are a marmite mod - but with my car being black with black wheels, I think the yellow could work. Nephew has them on his black M3 G80 and they work. The Z4 has a different DRL arrangement, so might not quite have the same impact.