I have no idea at all about buying an electric bike. what should i look for and what's a good price to pay. do they have to be registered?

E-Bikes vary but most commonly you have two varieties - fairly lightweight ones which will do around 40 km and bigger ones which will do around 80km. For the bigger bikes you'll be looking at around 3500rmb while the smaller ones anything from 2-3000. THere are a few really powerful ones which may need to be registered but most dont- check with them at the shop.
In my experience its all in the brand. I've seen a lot of people buy bikes that look cool or seem fast only for them to fall apart rapidly or the battery die in 2 months - Batteries, incidentally, need to be replaced annually and cost around 700rmb. The two most popular and well reputed brands are Xite and Lima both, i believe, manufactured in shanghai. Check what's offered in the warranty.
You would not believe how commonly these things get stolen so make sure it has a good alarm and you fork out a little bit extra for a good lock. These bikes take around 8-10 hours to charge so ideally you want to rent a parking space which also allows you to charge your bike... I paid around 50rmb for 3 months.
Hope this has helped;)

@maudiodj
awesome info, thank you.

@fogdear
perhaps you'd consider a push bike? no need to charge it; has no batteries needing replacement; minimal maintenance costs; better for your health; takes up less space when parked, and if you ride it enough, you can exceed the range of an electric bike :)

I have a regular bike and enjoy the exercise. just need an electric bike to take my daughter to school as it's a bit too far to bike. Feels like I've already exceeded the range of an electric as much as I've ridden lately. ;)

I've owned two different ones never registered and never a problem with the police. One was a 48v and one a 72v. The voltage, I believe, depends on the amount of batteries you have. All batteries are 12v so 4 batteries 48v and 6 batteries 72v. (Correct me if I'm wrong) The 72v goes faster and lasts longer, pretty obvious. However, contrary to mdj I've found they top out under 50km. I'd love to get on one that went 80km. A friends speedometer registers his at going over 60km but when we ride together mine is faster and registering 45km. I have learned to ride as slow as it will go and the charge lasts longer plus it seems more fun to me to ride really slow. The 48v was stolen from the underground parking, guarded with guards cameras, at the elevator of my complex at the so heed the warning of mdj!!!! Always keep it locked and always try to have the parking guarded(ha ha ha!!!) If you end up in the middle of town many of the buildings have pay parking. Usually 1 or 2 kuai. Also, they are a great way to explore town, but know your electric gauge. Just because it says you've got half a charge left doesn't meant you've got enough charge for the same amount of distance you've just covered. When mine reads half I head for home! What else...the things make no noise!!! Nice for on vehicle conversation but pedestrians about to walk into your path can not hear you coming so be careful! Happy trails and welcome to the club! Maybe we should start a gang!

I'm grateful for the valuable information in this thread. One thing I can't understand about these bikes is the function of the alarm. It's stated above: 'make sure it has a good alarm '. I regularly have e-bikes parked outside my home and alarms contribute only to noise pollution. Alarms are universally ignored (just like car horns) and I have to admit if I saw a thief making off with a bike known to have caused me angst at 0300 I would feel nothing but gratitude to the miscreant. Thanks to the info above I'm one step closer to buying a bike however, the unsociable and pointless alarm will be disabled on day 1.

Thanks for all the info. Charlie Heath, you say 4 batteries 48v, and 6 batteries 72v. The bikes have just one battery inside right? So the 72v battery would just be a bigger battery right?

Is it possible to take the battery out and bring it to charge in your house? My bike lot is way at the other end of my apartment complex and I'd prefer to save the 25rmb a month they charge and just park in my hall and bring the battery up to charge. Is that possible?

in the smaller bikes the batteries are in a sealed unit with a handle but its very heavy. Often with bigger bikes there are 4 small batteries so carrying isnt really a viable option.

I've seen some scoots that you can take the battery out but you can't on mine without a screwdriver. I'd suggest paying the extra 25 a month for secure parking. Does that include charging? There may be an additional fee for charging. Our building charges 20 per month to park securely and 40 per month to charge. It's the best way to spend 60 beans. I tried to not pay the fee and mine was stolen from our garage. They charge 2rmb per charge when you do it once at a time. I was trying to save cashish by not paying the 40 per month and pay the 2 per but I'd find myself not charging everyday and than worried I'd run out of juice. Now I just charge it no matter what every time I return and it's always ready for me to cruise around on. If you think about it you'd spend more than that on a round of drinks at Uprock or a meal at the Wicker Bucket!

I've been thinking for a while to buy a used one for around 1000. Is that a good idea? What can be the worst problem? A bad battery? Maybe I buy the bike and add 700RMB for a new battery? Or I go for the cheapest new one? But I don't want to buy a very crappy one.
And where to buy a good lock? Maybe overseas so chinese don't know how to open it.