What you're describing is called segmentation.
Probably the easiest way is to guess how long it would take you to make. Figure out what you're time is worth to you (do you want to make $5/hr or $15/hr). Multiply the time you think it'll take and what you want to make per hour and get a price. Then if the price seems reasonable, I'd charge that. If not, adjust it higher or lower as needed. Don't undervalue your work, though. Its a trap creative people often fall into since we tend to be overcritical of our own work.
I'd give a price on the upper end and gauge their reaction. Say "I normally charge $xx for something like this." If they think nothing of it, charge that price. If they're a little taken back, tell them "But since I know you, you can have my 'friend price' of $xx" and reduce it 10-20%.
Remember, it's always easier to reduce price than raise it.
You can read an article I wrote about pricing your work at: http://www.scrollsawvillage.com/village ... mber-2009/
You can also check out Etsy.com and search for others doing similar work and base your price on that.