this thread's OP and decision is
What the hell are you asking?
You pretty much said "I'm buying this gun. I don't care what you say, I'm just saying that I'm buying it....
I bought it. Guys I bought it. Say what you want, but I bought it. Quick, tell me before I get bored and forget."
I feel sorry for you if you make all your decisions like this.
but on a serious note:
The kaos is pretty good, $50 is average for a like new/brand new Kaos, especially if not from a store and the 2010 model (which it is since it's all black as said, I don't think they made an all black 2k11 one)
Now... That being said, it's a solid gun, but it has a ****ty cupvalve.
2 ways you can prevent that from becoming an issue permanently (which I would do only once it goes into the ****ter the first time)
1. buy a better valve. NDZ SS valves are super cheap (like $25 new kind of cheap) and are super durable, flow higher than the stock valve, and are just better all around.
2. you can buy a spring kit like the Maddmann spyder spring kit. replace the valve and striker/mainspring with a medium one from the kit. Don't clip the mainspring, it gives it enough tension to stay consistent and at a higher velocity.
Both ways will require you to mess with pressures a tiny bit in order to get he gun back to shooting ~280 FPS and are well worth it.
If you want to further upgrade it later on, see to finding a used Bob Long Torpedo regulator and a nice quality barrel that is coker threaded and has a bore between .678 and .685.
Avoid a sub-.680 barrel if you live in super humid, cold, or hot places like Florida, Somalia, Venezuela or the Yukon.
10" to 14" is optimal for barrels. Obviously your choice what barrel you end up with.
Some suggestions would be these: MacDev Matchstik, Disruptive barrel, Thin Air Sports GnB kit, Powerlyte Scepter, Empire Revolver, Lurker Eigenbarrel (one of the best), Dye UltraLite, Freak kit, MacDev Shift, Furious Lotus, J&J Edge, CP One Piece Classic or CP One Piece Tactical, some others I am forgetting atm.
Totally forgot to tell you: Buy a dow33 based or synthetic based lubricant, some gun/pneumatic tool oil, and a full set of ball-end standard hex/allen keys right now or ASAP. These are pretty much mandatory for any paintballer/bicylist/mechanic. Pretty much.
Get metric hex tools if you can, but not super necessary unless you buy a Vanguard, Angel, Planet Eclipse, or Smart Parts/GoG/DLX gun.