Go with OEM but I am not sure I would pay extra to have them installed at the port. When I ordered my 13 they were like $900 installed. You can get them from vendors here for around $500. They are a breeze to install. I just installed mine last weekend. All you need is a drill and some 3M molding tape. Feel free to PM me and I'll walk you through the install.
2013 M3 Coupe/DCT/ZCP/Speed Cloth/BMW Performance Exhaust/Dinan Goodies/CF Bits/Volk TE37 SL