Piratecycles.kom has the Grubee GT4 Starfire engine kits on sale for $150.00
Grubee Starfire Gt4
Here's another kit for $129.95 I checked the shipping cost and to Central Texas where I am it's just $29.00 Fedex Ground,
80cc Silver Slant Bicycle Engine Kit
I dont own the " RAW " kit but I have heard other speak highly of there kits, I personally have BGF kits and have had very good luck with them, some need mor tweaking than others but in my opinion, all of these engines are a crap shoot no matter what sticker someone puts on them, ytou can get a better than average engine or you can get a not so good one that will need more smoothing up internally for it to perform well.
I think a lot of Thats Dax and have made multiple orders from him and I am a very happy customer of his but personally there is no way I would pay $300 for a china girl kit no matter what the claims are, there's not a dimes worth of difference in any of them IMO, I know some will argue different and make high powered claims on curtain "brands" but for even these claims there are other out there who have got a piece of crap with that same sticker on it, so I say shop based on what you can afford if you can pay a little more because you want better customer service, then that option is there, or if you just want to get out as cheap as possible and you plan & are able to resolve any engine issue on your own, then go with a RAW or a BGF kit and you'll likely have just as good of engine as the higher priced "BRANDS", some come with extra parts and gaskets and stuff like that, but in my experience of looking around at all the kits, most all of them come with the very undesirable 44T sprocket IMO, and you can get a kit with a 41T or 36T sprocket from BGF cheaper and have a faster set up when it's all said and done, and BGF has always answered my email very quick, but he doesnt offer a great warrantee so there is a risk in that area, but as cheap as parts are from him and others I dont care about that, I'll take that chance and so far I've had zero issues with his kits, my 39MPH bike has a 66cc Slant BIG MOUNT BGF engine and is a nice cruiser @ 30-32MPH with a 36T sprocket.
Just go with your own gut on it but DONT over pay, ther eis NO advantage to spending more money for the same crudely made china built engine.
Peace