the Daisy Powerline 853 is probably one of the best choices out there for the beginners.
it's not really very cheap though...
it comes with good diopter sights and is a single pump pneumatic with an advertised 500 fps MV...
a HIGHLY accurate air rifle...
other than that there are some lower priced Daisy air rifles that will fill the bill quite nicely.
www.daisyairguns.com