Wildlife photography it tricky, so I'll give you a bit of my procedure on shooting birds and how shake-reduction (the Pentax equivalent of VR) helps out.
First off, shake-reduction will allow you about 2-3 stops extra of being able to hand-hold a camera for a shot. The general rule is if you're using a 300mm lens, your slowest shutter speed to hand-hold is about 1/300th of a second. With Shake-reduction, you can get away with a shutter speed of around 1/75th or 1/50th of a second. This will yield sharper images if you're in poor light and allow you to use a lower ISO for better overall quality. However, shake-reduction only helps you out. If you're naturally jittery, you might only be able to get away with 1/150th of a second.
What VR won't do is freeze motion blur from your subject moving. This means if a deer moves it's head while you're exposure is going, you'll still end up with a blurred picture.
All that being said, I use shake-reduction and a tripod when I shoot birds because the mirror-slap will mess up critical focus when I'm around 1/60th of a second on up to 1/200th of a second. The tripod keeps things stable and the SR keeps the vibrations from the mirror-slap from messing me up. I also put a hand on my lens (over the point where the tripod head fastens to my lens - not an issue for your lens) to help dampen vibrations from the camera.
If you're thinking this will be "the one" wildlife lens and thats where your main interest lies, then VR would help you out quite a bit and you'll be glad you spent the extra up-front. If you're thinking this will hold you over for a year or two, then get the cheap one and save up for a fast lens.
Cheers!
