Carburetor for a 150cc znen joker clone?

[MClara]

I've had a znen 150 for a couple of years now--this is my third summer. It was having a heck of a time starting and initial acceleration was flat. I took it to a local shop and they got it running somewhat better--said they cleaned the carburetor, twice, with ultrasound. But it's far from optimal and they said a new carburetor would take care of it. They said the cause of the problem is ethanol in the fuel and recommend I add a stabilizing enzyme to every tank of gas. They want $80 for the carburetor, plus labor, which will make it as much as $160. I looked around online and the most expensive carburetor I can find for a GY6 (which is what I've got, right???) is about $40, so their costs seem more than a little high. Maybe I should do it myself? What carburetor should I get for it, and from where? Thoughts on what this shop wants to charge me? Maybe they're right on the money, what do I know...

Here's the scooter:


Here's the specs:

Engine/Drive Train
Displacement: 149cc, 4-Stroke
Horsepower: 8.4 hp
Max Torque [n.m/(r/min)]: 6.7/5400
Cooling System: Air Cooled
Transmission: Automatic
Drive: Belt
Starter: Electric / Kick Start
Ignition: 12 V 7AH
Top Speed: 55+ MPH (Depending on Riders Weight and Road Conditions)

Thanks!