I bought myself a Benjamin Trail Nitro .22 similar to this for Christmas. Comes with a shroud on the barrel that is actually a modest suppressor. That and the nitro piston take a lot of the noise away from what high power airguns usually have. Came with a decent scope as well, a bit over $200 at Sports Authority.
Will smack a pellet through 1/2" plywood, so a rat/squirrel would be no problem, and it is quiet enough so the next door people should not suspect much.