A member of the ES forum has some TF S-750 bikes without motors or batteries for sale. He bought a bunch when the company went out of business. They are very good. Then just find a good ebike kit from Amped bikes or Grin technology, 9C motors and put them together for a great bike. Here are some links:
For
ES forum
Amped bike
http://ampedbikes.com
/buynow.html
Grin