Bionx and EZee were the ones I was familiar with at the time of the big boom.
One Retail Dealer had ordered 50 Bionx kits, and sold all of them. so did all the other big Bionx dealers.
Many bright People were still worried about battery longevity/ overall reliability and would pay a little extra for local service.
Eric Sundin did very good with his EZee prebuilts, as did NYCE.
There were lots of phone calls from people with "off Brand" ebikes, no prints, manuals, or parts. sometimes it was an easy fix, but usually could not help them for the price they wanted to pay. Lots of complaints for repair estimates exceeding 50% of the cost of the ebike. But when you have 6 pallets of $1.5k ebikes to be finalled and bills to be paid by building and selling them, your 'free hours of advise' quota goes down quite a bit.
Some give-away service explaining why cheapo generic SLA batteries would not work on high powered low voltage systems.
Then the salesy 20 questions of how to pick out the right ebike; fit, enough power, speed, enough range. One place generated some handouts, and gave them out when the line of customers was too long. Finally posted a big handout on the wall.
EZeepre-builts did not have an owners manual, so care and maintennce instructions had to be typed up and copied. Then nitpicky people laughed at the typo errors.
quite a few of the people here were probably involved in different phases of that craziness.
with todays credit market the way it is, It might be somewhat different the next time though.
d