Tell me how much to charge for my portrait art

I've been getting a lot of orders for some portraits, so I was curious as to what I should charge. I know that price can vary slightly with the job, but I just wanted to see what some of you would expect to pay for some of my work. They are usually on regular, typing paper-sized sheets (because I usually just use pencils) but I'm willing to do them a little larger, if requested.

http://img.photobucket.com/albums/v6...aCopyright.jpg
http://img.photobucket.com/albums/v6...eCopyright.jpg
http://img.photobucket.com/albums/v6.../Mona_sboy.jpg
http://img.photobucket.com/albums/v6...ch_sFamily.jpg
http://img.photobucket.com/albums/v6.../AliLandry.jpg

Most often, I charge about $60 for one person - black and white; about $80 for 2 people.

Roughly $80 for one person - full color; and $100+ for 2 people.

No one has really had any trouble with those prices, so far, but they were just arbitrary fees I came up with. How much would you pay for a person of your choice? Do you think they are worth more?

They can take me from a few hours to a few days, depending on how busy I am and the level of detail.