3x9x40 is pretty reasonable, though there's nothing wrong
with a fixed 4 power if it's a deer-hunting rig for shots out
to 300 yards.
If it's not a magnum cartridge that you are shooting, I'd
look closely at Bushnell Elite 4200, or for a little less, the
3200. Reportedly, these are great scopes, but I've been
led to believe that eye-relief is a little meager, so putting
one on a heavy-recoiler might be a problem.
My last scope purchase was a Sightron SII series 3x9x40,
also a great scope for the money.
Nothing wrong with Leupold scopes, but they are a bit
more expensive than the above for a comparable quality.
The down side is that they cheat a little bit on their
magnification. In other words, a 3x9 power Leupold does
not quite get down to 3x nor up to 9x (it's more like 3.3x
to 8.6x).
I've got several Swarovski, Zeiss, and even a Leica. All
are great scopes, but like the custom vs. stock rifle
discussion, it's not necessary to spend that much money
for good optics unless you just can and want to!
For more information, you might want to check out
www.chuckhawks.com. Look for the "guns & shooting
online" option, then go to the "scopes & sport optics page,"
then look for "selecting & buying scopes & sights," which
should take you to "scoping it out," by Randy Wakeman.
Another source of information that I found helpful was
www.shortmags.org. Look to the right, under
"guides," then hit the "scopes" option.
Good luck.