Hi Noyloj!
I'm new to this as well and definitely not an authority on any of it. But, I've read a lot of forums and gained a lot of insight from other members. You can look at the side of the carb for the model. If stock, it should be a vb42a. Verify that first.
If that's what you have, kits can run from $30 USD to $190 USD. I've see a lot of complaints that the cheaper kits don't have the parts that fit "quite right" or missing some key components. Some people rebuild them with all new parts while others never change anything, but merely clean what's there. It'll depend on condition and your attention to detail.
With my rebuild I had to purchase new float bowl gaskets, float drain screws, rubber slow jet plugs and an o-ring for the accelerator pump amc49 mentioned. (If you need this and it doesn't come with your kit let me know or look at my "for sale" thread on his forum )
Another thing that seems to be repeated throughout is that it's highly unlikely your carbs are why it's not running. It may be a failure point for sure. But, before going all wild and crazy with jetting etc., make sure you've adjusted the cam chains and checked/adjusted the valves. There's lots of posts and videos of this information. And get a service manual! (Also found online for free)
My personal "not siezed, not running" bike progress is as follows: clean tank, clean Petcock, change fuel line and add filter, clean carbs, adjust cam chains and valves, change oil filter and plugs, new battery and see if it will run before proceeding. If all goes well, check charging system and compression. Once all that's done, adjust for running smoothly. Then move on to drive train (clutch plates, chain, sprockets etc. ) and brakes. Get it running, get it moving, get it stopping. Is this the right order? I don't know, but time will tell. Best of luck!
Also, definitely download seang's carb manual and read it several times before getting into them. You can search for it or maybe someone will chime in with a link.