I got some nice //M ones for like 4 bucks shipped. use them in teh summer. Use Plastic ones in the winter as the salt/moisture + metal caps do not mix in the winter.
2011 335i X Drive Special Edition-Jerez Black
35% Tint All Around / 3M Rockguard / Weathertech/ PPK2 / 18&12mm Spacers/Lux H8 V3