The clones tend to run around 40-60 bucks and the real deal is about 105 or so. They use a 23mm O.D. intake tube, so you will likely need to figure out the intake side.
Me, I bought one geuine VM18-144 from Niche cycle a few years back for 80 bucks, and I still have it for future engines later down the road. An 18mm carb is perfect for 50-85cc engines, and on the 66cc or bigger engines it provides a great balance of power and tunability.
The VM-18 also uses 32mm filters, which means there are several scooter filters of different shapes and sizes that fit it which can really help with tight frames.
Hey! Does that answer your question? Lol there's alot more involved than that but by this point I'm. Pretty much the guy your looking to talk to lol msg me.