My idea of the ideal bike should be:

1. Standing like Dreamslide bikes http://gajitz.com/standing-ovation-p...-like-a-dream/ or this http://www.toxel.com/tech/2010/11/07/stepper-bicycle/ - no back pain, neck pain

2. Possible to put a big trailer so as to put belongings and grocery
3. Has engine so that when you are tired, you can cruise with the engine - or your pedaling charges battery which could be used when you are tired.
4. Foldable so that you can put it in your car
5. Three-wheeled so that you can never slip and fall and hurt yourself

Here's electric folding bike for $280: http://www.kingsmotorbikes.com/kmb-e...g-bike-blk.htm


I'm thinking of something like this (A tricycle with big trailer): http://en.wikipedia.org/wiki/File:Ma...adu,_India.jpg
Another tricycle: http://en.wikipedia.org/wiki/File:Workhorse_Trike.jpg But its container is too small to carry enough stuff.

If the trailer was long enough I guess you could even sleep in it with a small opening for air.

So basically I want: Stand-up tricycle with engine attached.

I found an electrical tricycle with a small large basket in the back and a basket in the front: http://www.saferwholesale.com/EW88L-...ewh-ew-88l.htm
Electricity might be more expensive than gas, and the baskets might not hold as much as I want. And way too expensive.

How might I be able to make a stand-up tricycle with engine attached? How much money would it cost?