its not an expensive thing at all.
I charge a base 400 for 16Vs...........and silly mods like forged pistons cost 600 quif for the F7, viper costs 250, chips cost 250......so, interms of VFM and total potential output, nothing really compares.
And contrary to what Alex said, there is alot of science to it. Theres not much to the ideal shape, but no production engine is even close to ideal. So you do the best you can within constraits.
Your also thinking of boundary layers, benefits are 2 fold. Prevent fuel drop out, create turbulance agains thte port walls, at slow velocities the middle of the port flows faster than the outside of the port.
Port volumes, shape, radii, valve shape and size, length, texture and more than i can be bothered to go into for no particular reason (money).
I could easily spend far too much time telling you all about it and what to do, but even then only a spall portion would be able to do anything worthwhile with the head. Its just the way things go, otherwise there would be no big names in this specialist area.