It should be pretty easy to find someone to do it in that area. Generally theatrical and special effects make-up stores know people who do life casting. I was considering having one done by the guy who works with the local theatrical supply shop in my town. Also sometimes art supply shops know of people who do life casting as well. To give you an idea of the cost, it was about $400 to have a single copy done in plaster.
From personal experience, I would not recommend doing it yourselves if the person doing the mold material, whether it's silicone or alginate, is unsure of what they're doing. Me and my husband made three attempts at doing a head cast and all three failed. While we were using alginate, it was a rather frustrating and expensive endeavor. Yes, I did get some in my nose but the big thing is not to panic and just forcibly exhale through your nose and blow it out without moving too much of your face. Also, make sure that you have multiple people helping you and not just the two of you. Head casts are rather dangerous endeavors if you are not familiar with what you're doing. There's a wonderful thing called mold lock that can happen. You don't want to try to explain why you need someone's head freed from a block of plaster. If you're determined to do this on you're own I would -HIGHLY- suggest purchasing one if not two professional videos on life casting and starting with a small body part like a hand or arm so that you understand it before doing something like your head.
Here's some DVDs that might be of use:
Lifecasting 101 - This one is only about alginate but as I understand it the process is very much the same with silicone. I have this one and it's a pretty good over view about how the process works. Very informative and affordable. They also have a rather affordable alginate head casting kit.
Introduction to Life Casting - This one is produced by Smooth On which has some wonderful skin safe life casting silicones. They have one now called Body Double Silk which does not require the addition of a release for short hear like eyebrows and close cropped beards.
Mark Alfrey's Ultimate Lifecasting - I haven't seen this one but it was among the ones recommended to me.
Stan Winston DVD: How to Life-Cast - I've heard that this is the end all be all but the price tag was a little to rich for me.