Here are some con sketches that my wife and I obtained when George was recently in Perth. The first was included in the price of the particular entry tickets we bought. The other was an extra piece that I paid George for, which admittedly may be a little more detailed than normal based on the size of the page and the fact that I had already paid him for a full-on pre-commission sketch that I had picked up the previous day.
I was going to ask him for Green Goblin, but the guy in line in front of me asked for him first. That turned out great as well.
The other piece we got (Luke Cage) included in the price ended up going to a friend, and I can't locate a picture of it at the moment.
Basically, you're much better off going for a character with a more complex-looking face than one with a full-face mask if you're looking for bang-for-buck.