Surfin the net for where to buy cobs I came across this DIY thread
IMO, no need for the E27s as overheads. Instead, position them so the sockets/bulbs face down. Add extenders and they are perfect for side/below canopy lighting
Feast your eyes on this...
http://howtogrowmarijuana.com/DIY-LED-grow-light
Feast your eyes on this...
http://howtogrowmarijuana.com/DIY-LED-grow-light