Megillot by Jen start at US$1500. Exact price will depend on schedule and degree of ornamentation. You may now book a megillah for delivery after August 2010.
Mezuzot by Jen start at US$250, and in sizes no smaller than 10cm. This is a ridiculous price, because I don't much like writing mezuzuot; they are very small and fiddly, so right now if you want a mezuzah from me you have to compensate me for spending all day crunched up and getting a headache. I have students and colleagues who don't get headaches from mezuzot, and they charge much more reasonable prices starting at about $40 plus shipping, so contact me and I can fix you up.
When you commission a Torah, you are employing me to write for you full-time for a whole year. Pricing reflects this.
I'm not presently doing tefillin, cos they're even smaller and fiddlier than mezuzot, but if it's really really important to you, get in touch and we'll talk.