how much will the vc games cost?

No one has any idea. Some may be free for all we know, they may be $5 for old ones, more for newer ones, or flat pricing across the board. We won't have a clue until either Nintendo releases the info or we have the consoles in our hands.
I can't see them exceding more than $5 for any game. The old N64 games are $15, which I have no idea why. But the NES and SNES games should be about $1-$3.
or in uk money £5 N64 £15
Or use ebay r your local car boot to pick up some bargins
I've heard anywhere from 5$ to 15$ American. I'm sure the prices will change from console to console, though.