Look--I do this 'cause I love it.  I'm not expecting to buy a house or take a cruise.  Just pay me for the yarn and whatever you think the project, my time and effort, and my impeccable artistry (whoa, sister, let's get that ego in check!) are worth.  This is where I throw in "the joke".  Wanna hear the joke?  The joke is this:  You--"How much will this cost?"  Me (in feigned modesty)--"Oh, I refuse to charge anything but the cost of materials and nothing more than minimum wage."  Now, minimum wage where I live is $9.36 an hour.  An afghan can take upwards of 50-70 hours to complete.  That's, like, $500 PLUS the yarn!!!  NO FRIGGIN' WAY I'M GONNA CHARGE ANYBODY $500 FOR AN AFGHAN THAT YOUR SIGNIFICANT OTHER'S GONNA THROW UP ON DURING THE NEXT BINGE!!  So, reimburse the yarn and then something fair.  Let's call it a "sliding scale".  You slip me a few bucks and then you slide out the door before it hits me how much I got ripped off.  I just want to be able to go KFC every once in a while.