Hi Breeno - this is how we pick good oil bats, that tend to last seasons & seasons.
Drive to Adelaide or your local city one afternoon.
Go to one of the Cricketing Mega Warehouses located there. Ask to go through the bats out the back - they should be in racks labelled brands, styles and weights.
Work out if you want a heavy bat or a light weight - Light Weight = 2lb8 to 2lb10. Heavy Weight is 2lb 10 plus. Find a weight your happy with. Pick out a few different models of Gray Nic, Kooka model etc correspondent to the price tag you've mentioned. There will probable be 10 -35 bats in each rack of correspondent brand, styles & weights. Go through each bat and check the grain is straight down the blade and that the grain flows straight through the toe of the bat and not on an angle or crooked. Check that no knots are also in the blade and most believe 5 - 7 grains is perfect.
You have now probably eliminated all but maybe 10 in each rack which originally contained 35. You should now have 10 kook's, 11 gray nics & 9 GM's etc or 30ish bats total. Now stand in your batting stance and pick up each of these bats a couple of times as if the bowler is just about to deliver. You will know notice that though they weight the same - some have a better pick up that others ... ie they feel lighter. Unless you want a toe heavy bat disregard the half that pick up heavily. You now have only 15 bats to choose from.
Now get a ball knocker innerer on a handle and tap the blade of each bat until you find the 1 in the 15 that has the best pick up & very sweetest middle and blade -THAT IS THE BEST VALUE BAT FOR YOUR $300 - $450.