I just bought a Nikon Prostaff 3-9x40 in Silver for my Ruger M77 Stainless/Synthetic .30-06 at Dicks Sporting Goods for 149.99. After I bought I found it brand new on eBay for cheaper than that. The best part was that I got it in Silver!
I would definitely go for the Nikon Prostaff 3-9x40, it is just as good as a Leupold VX1 and not quite as good as a VX2. My theory is, this is going to be my knock around gun (actually take it out of the safe and go deer hunting with it). So if something happens to the scope then I'm not out $250+. However, if you are looking to shoot it at the range (which would be a LONG day with a 300WSM and probably not the caliber of choice for target shooting), I would purchase a higher power scope and spend more money.
For what you are going to use it for, the Nikon should do just fine. Just my .02...
It's all fun and games until a piece of hot brass goes down your shirt...
Imagine if every outdoorsman taught the sport to 2 young people -----> What are you doing to save our sport?