Well, if I were you, and I know this is something very different from a pocket bike, I'd get a Go-Ped. I don't want to make anyone mad or anything who are big into pocketbikes, but the Chinese ones just aren't worth it.
I have a Cag, and I haven't had very much trouble at all with it compared to most, although a lot compared to my Go-Ped. Chinese pocket bikes take a lot to maintain and a lot of work if you don't treat them right. Recently, I just got my pocket bike fixed after one of the exhaust pipe engine mounting holes stripped from me continuously having to tighten it from vibration, even with red loctite; it had been sitting for about 4-5 months (my fault; I was tired of messing with it).
If you're planning on putting any money into what you buy, a Go-Ped is your best bet as in the long run, I don't really think it's worth it to spend money on something less reliable and less maintenence friendly when you can get your money's worth with something more reliable such as a Go-Ped.
I like my pocketbike, but not as much as I used to as I've come to my senses that it's kind of a waste to spend money on it. If you are willling to spend the money to get a Blata 2.5 (more than $400), then get that, otherwise, I'd get a Go-Ped.
There is the S25 (http://www.davesmotors.com/store/product3.html
) for $300 (and remember, this is American made, not Chinese, although the price makes it look so) and the Sport (http://www.davesmotors.com/store/sport.html
; $365 showroom model: http://www.davesmotors.com/store/product473.html
) for $400. The S25 goes a little faster than the Sport, and is twice as efficient (It gets 200mpg, or a little more than 52.8 miles per tank), but has less available modifications. The Sport, on the other hand, goes just a little bit slower than the S25, about 17-18 mph compared to the S25's 19-20, and get's 100mpg/26.4 miles per tank; however, the Sport has a TON of modifications available, including more powerful motors (the next motor up from the stock motor (1.2hp, the motor on the S25 now has 1.2, down from 1.5) has more than twice the power; the motor I have on mine had 3.5hp stock, and makes almost 5hp with my pipe), which the S25 does not have.
So, if you decide you want a Go-Ped, then get a S25 if you plan on keeping it pretty much stock, or a Sport if you plan on modifying it in the future (there are hundreds of modifications for it, literally). Now be forewarned, neither of these will go as fast as most Chinese pocketbikes, although they're far more reliable. My Go-Ped accelerates like a rocket compared to my Cag, and is faster, too, but I got a new motor over Christmas that's more powerful (as I previously said) as the motor I had on it was getting old (it's a 1999 motor; I bet no Chinese pocketbike can last that long) and it was about time for a rebuild, although it still ran great, but not as good as a new one would. I imagine it had at least 1,000 miles on it, probably a lot more.
If you decide to get a Chinese pocket bike, then plan on working on it fairly often. If you have someone that can help you work on it if you don't know much about working on things than you should be in pretty good shape, but I think it'll have almost as much down time as the time you ride it. Although if you can get your hands on a nice Blata 2.5 for cheap (which I don't think you'll be able to do, as I've never heard of one as cheap as $400), then that'd be your best bet.
Anyway, I hope I've helped out. And please, no one spam me, it's just the truth about pocketbikes. I've had my pocketbike about a year and a half and was really into it until I did some major upgrades to my Go-Ped while my Cag was sitting around for months needing to be fixed, so I'm not as into it and know better than to spend much more money on it (unless I put a Go-Ped engine in it, I think a Komatsu-Zenoah G62PU, 5.4hp stock which a sh!t-load of torque; but that's very unlikely, plus I could probably just get a nice European pocket bike motor for it, both of those options costing a lot of money) as it's not as reliable as my Go-Ped.
P.S. I'm 14 and in the 8th grade, too