Ebay bikes?

Hey guys,
I'm looking to buy a pocket bike so i can muck around in my street and pull mono's and stuff.
I've been looking at the ebay bikes, pretty cheap. I know they're Chinese CAG's, whatever that means...but i've attached a pic, can you see how in the top pic (ebay bike) the rear swing arm and frame seems a bit flimsy? I don't want it to break if i'm on the rear tyre pulling mono's.
THe bottom pic is a bike off this forum, see how the frame is much sturdier?

Can someone point me in the right direction, where i can get a cheap bike, i want to spend about $300 AU max for an ebay bike, but just don't know the quality of the frame n stuff...

If anyone has bought one off there or knows about them off there, can you please help, thanks.

i have a cag for sale with a sh!t- load of spares. only been ridden once- dead set genuine ten minute old motor. check the for sale section. and i am negotiable on price as well

I bought a CAG for a friend of mine from oz auctions on ebay and after a few teething problems its going well now. The frames on these are strong too.