SLK/R171: Wind Deflector (draught stop), any aftermarket solutions, or is OEM the way to go?

1. What is the OEM part number
2. Any online retailers recommended to find the best price?
3. Are there any aftermarket solutions that are recommended?
My friend is hoping to not spend $600 for a wind deflector, so any help in finding a solid solution will be helpful.
Thanks in advance.
1. OEM all netting, $170 online
2. OEM plexiglass and netting $650
3. Wind Restrictor, plexiglass that bolts onto existing threads. $240 and up depending on options



