Not that long ago I got bored (I know a very dangerous thing), and I crunched some numbers. If I were to sell my MTG cards (I won't any time soon) basic lands for a nickel, commons for a dime, uncommons for a quarter, rares for .50$ and mythic/other for a dollar it would total to this:
Amount price
basic lands 1949 $97.45
commons 3057 $305.7
uncommon 1067 $266.75
rare 290 $145
other 41 $41
total 6404 $ 855.9
For an average price of $0.13 (or so) cents.per card.
Or if I shifted every price down one it would be IE A penny for land, a nickel for common ect
Amount price
basic lands 1949 $19.49
commons 3057 $152.85
uncommon 1067 $106.70
rare 290 $72.50
other 41 $20.50
total 6404 $327.04
Which would average to be about $.06 per card.
And for those of you who are interested, my average spell's CMC is 3 and my average creature is a 2/2. I don't know if this holds true for the entire game, but if it does, that explains morph.