Online try pocketbikeparts just do the www. and the .com thing. They sale parts, but the might sell bikes also. Do alot of bizz with them. They have a toll free phone. If they don't sell bikes they can probably tell you where to look.
Look at the Ads on this site, there all over for pocketbikes, find one, click on it and it will take you to search engines that have pages of pocketbike dealers and parts. There is PocketbikesUSA in Texas, but have not heard any good things about them. eBay is a good place to look also. I like dealers w/ phones, I call and ask them if there in stock before I buy, so there are no excuses when your bike don't show up.
Also, buy w/ a Visa ATM or credit card, they will back you up. eBay/Motors/motorcycles/ 49cc pocket bikes forsale, another place to look.
I also suggest you go ahead and get some 2 stroke oil with it as well.. Also make sure all the bolts nuts and screws are fastened tightly. bottle of loctite might come in handy in the near future aswell. A check of all the major mechanical components is always good before even starting the bike too, might save you some money on parts down the road, since these things break/malfunction all the time and are likely assembled by 14 year olds in China.