Two things you can't buy are patience and perserverence. Patience keeps you out there hunting, and perserverence gets you out there again.
However, clothing would be the number one thing that helps make sure you have enough patience and perserverence. I used to tote a very expensive rifle and scope out deer hunting dressed in cheap K-Mart tube socks, six pair for a buck, and suffered through the season, rather than enjoying it.
I actually pick up a lot of my hunting clothing at the local thrift shops, looking for heavy duty flannel shirts, wool pants, and nice turtleneck sweaters. I even bought a brand new pair of insulated Snow pac boots for 10 cents, though they had no shoelaces.
My coat is a nice L.L. Bean one that I ordered though, as sometimes value has to override cost, and I love that coat even at twice the price.
Binoculars and a nice knife are two other places to look at value rather than cost, since the extra money spent will be spread out over a lifetime. Get the best you can afford with these two items, and you won't regret it fifteen years from now.