This may not be as custom as you're hoping, but you could get a knife kit, make any changes to the handle/etc., then have a local machinist reshape the blade a bit. Texas Knifemakers Supply sells kits. And I know a guy locally who has designed some knives in the past and does knife sharpening as a side business who can re-shape a blade (to within reason). I'd gather you can find a similar service in a lot of towns. (Of course, could take some time trusting them to take a big cold grinder to your blade.)

Anyways, may not be just what you're looking for but it wouldn't be as expensive and probably a lot faster turn than a full custom jobby.
J