I have a couple, a TalonSS and a XS-B50. I think Leftcoast said it, the TalonSS is adjustable and somewhat quiet, whereas the other two have more power and are less quiet. I don't know about the AR6, but I know the other two sometimes have "issues" out of the box, but not always. Personally in your pricerange I'd be looking real hard at the Air Arms guns. The S200 is a lower powered, but very accurate gun between 6 and 19 FPE if I remember correctly, the factory moderated version is pretty quiet also. The S200 is a single shot, but for $99 you can add a rotary clip...it's a little wonky to work, but not bad...I shot a friends for a few hours and I wasn't too irritated. The S400/410 is a higher powered PCP, the 400 I believe is single shot and the 410 is a multishot. Alot of power, very accurate, maybe a little heavy for hunting, but I haven't shot one with standard wood, although I doubt it's much lighter. For the money I think the Air Arms are the way to go. I like my TalonSS, but it's not a repeater, it's awkward to shoot, and they aren't always great without some work...the jury is still out on whether or not I will keep it:) It's not "super" quiet either unless you do some extra work on it. I would say mine in stock form is about as loud as my BSA Superstar springer, maybe louder at full power. Power adjustment with a standard 12" barrel is only adjustable until the gun is set to power level 2-3 out of 12, beyond 2-3 the gun just gets louder but the pellets don't go any faster. I wont comment on my B50 as it is just too much work to even think about right now. It was fun to shoot for the first 300 pellets or so, then it just became a headache.
Good luck!
