There are some parts of the design that you might not consider on your own. One great way to get a custom rolling is to post your thoughts on the dreaming board and have a good conversation here before you decide on, or bother, any dealer.
I'm not sure how much value there is in calling around for quotes. Alembic instituted a policy of maximum discount a few years ago and, if still in place, you probably shouldn't see any difference in the quotes. That doesn't mean a dealer won't throw in something to appear more competitive than the others, but price shouldn't really be an issue. Do a board search here and you'll find at least 2-3 dealers that come very highly recommended.
Another key issue, if the money matters, is that you examine the monthly specials and see which would be most advantageous to your design. Also, be aware that some features that might appear to be purely cosmetic have performance implications and should be considered. Among these are wood backplates, LEDs, and plated hardware.
-bob