Here's some data I have on confirmed sales (from March-April-May-June) just to illustrate the importance of grade and how much things may vary:
Amazing Spiderman #6 (1st appearance of The Lizard)
Graded 7.5 = $995, $1,000, $1,055
Graded 7 = $945
Graded 6.5 = $800
Graded 6 = $510, $670
Graded 5 = $450, $550, $550
Graded 4 = $306, $425
Graded 3.5 = $315
Daredevil #1 (1st appearance of Daredevil)
Graded 8 = $2,500
Graded 6.5 = $1,150, $1,200, $1,300
Graded 6 =$1,025
Graded 5.5 = $700, $720
Graded 5 = 610
X-Men #1 (1st appearance of Cyclops, Prof X, Magneto, etc)
Graded 5 = $2,180, $2,250
Graded 4.5 = $1,380, $1,750
Graded 4 = $1,660, $1,680, $1,800
Graded 3.5 = $1,500
Graded 3 = $1,270, $1,300, $1,500, $1,500
Graded 2.5 = $885, $1,000, $1,000, $1,200
Graded 2 = $860
Grades in comics vary significantly and prices reflect that.
When talking about comics from the 60's/70's/80's etc their condition ranges from all sorts of territory. Literally a 3.0 Journey Into Mystery (1st appearance of Thor) will always sell for $2,000.
So you have to really do your research and learn what you want to collect and the prices they go for. I say stick to the biggies- they are the most liquid, most popular, and will easily be the most sought after years from now.