The electric bike population has doubled between 2012 ans 2013, and the current trends indicate that it will double again in 2014. That equals a lot of newbies.
The top three retailers by a large margin are Currie, Pedego (rear hub cruisers), and Prodeco, with many E-bikes being sold through Amazon and Ebay.
http://www.ecycleelectric.com/blog/important-events-from-the-2013-electric-bike-industry
Everyone likes to read the articles on the slick new high-end E-bikes, but the vast majority are the "entry level" E-bikes, with the kits also selling well.
Even when a customer is reasonably satisfied with the performance, the batteries are almost all at an entry-level of quality and are usually too small, leading to half the rated life-cycle. Newbies want advice on minor trouble-shooting and what battery to buy next that will be better than the stock battery that came with the bike. Some drop off the ebike scene when their first battery dies, and others like it so much they want a second bike with better performance...and they are then willing to pay more to get something good.
If I need a LiPo wiring harness, I will get it from ES member icecube57 (Chris).
Methtek doesn't seem to be selling stuff anymore...
Bertie made optical sensors for RC motors
ZombieSS makes throttle tamers (adjustable throttle ramp-up to tame Cromotor wheelies)
kfong had a great LiPo LVC V4 battery protector (is he still selling them?)...