Don't listen to these guys. So far the input has been from a sub-par team in V, with little experience in IV. And an Australian player, who is not familiar with how USA IVs play.
At the very top level of IV(meaning you are a playoff team) your SG could run you from 800k to 2 million if you are an outside based team. My SG has 12 JS and cost me about 1.3 million.
If you are an inside focus team, your SG could be from 400k to 1 million. He just needs to be a roleplayer with good OD and handling and passing and possibly rebounding. A little jump range doesn't hurt too, because you won't be getting many threes.
If you are balanced, than your SG could be from 600k to 1.5 million. He needs to be a good defender of course, and have a little JS as well, but not as much as you'd need if you are outside focused, instead he could have extra skills in handling and passing and possibly driving.