There's a lot of stuff already in this thread, a few ways for you to get started, and a lot more roadblocks that might be in the way.
To address your original question, the cheapest way to access a waterjet cutter might be to find a college or technical school that has one and offers classes. Cost could range for a few hundred for a single class, or $10,000+ if you have to enroll. Keep in mind you'd likely need to familiarize yourself with CAD (which you may already know, depending on how you did your designs).
If you're a tinkerer and want to get your hands dirty, you could consider building a water jet cutter. It's non-trivial - you'd probably need an engineering background, a well-equipped shop, and some specialty parts. Also, I don't know of any internet tutorials, plans, or how-to guides, so you'd have to work a little blind (hence the engineering background). Building all of your knives with hand tools would certainly be faster and cheaper. Your time investment might pay off somewhere in the neighborhood of a few thousand blades (i.e. you could make a thousand knives by hand in the time it would take you to build a waterjet and then use it to make a thousand knives).
If you just want to see your design made, finding a willing maker and sending him a sketch would be the quickest way. It would probably run you a few hundred bucks, and be money well spent - then you could figure out if the blade looks right, feels right in the hand, etc. Prototyping is ALWAYS a good idea. Of course, you could do the shaping yourself, either for a fully-finished knife, or a soft-steel dummy model to get the lines right. If the prototype works out, you could outsource a few hundred waterjet blanks, outsource the grinding, outsource the heat treat, etc. However, on the scale you're talking (a few hundred blades per year), most makers do much of the work themselves, and still don't make huge amounts of money doing it. Outsourcing adds cost (in labor and shipping), so you'll have to charge more to make a profit. If you choose this route, you'll need a good business plan so you don't loose your shirt.
Penultimate option is giving a company a design, and letting them do everything. This could either be a "custom collaboration" - it's a Spyderco or Kershaw or Boker or Whatever with the design attributed to you, or the shop puts your name on it (A.G. Russell comes to mind). In the first case, you might be dealing with company structure in the U.S. (president, VP, whoever). In the second case, you'll likely need to travel overseas or have an intermediary who sets things up, and you'll also have to pay for prototyping, tooling, and materials, among other things. If you go this route, be careful with your designs - many less-reputable companies and overseas factories have pirated the designs of successful knifemakers. If you start mailing pictures around without signed contracts, you may see your design show up on the $5 flea market table with no mention of you and no money in your pocket.
Last option would be to get a copy of Goddard's $50 knife shop, adjust for inflation, and scrounge up some tools. You could probably have one serviceable knife in a month, and you'd be better at the "old school" tasks. Guys have suggested this because it's the quickest, easiest way for the average person to make a knife. The modern, technical way is certainly possible, but you need to add a few more zeros to the bankroll.
Regardless of which path you choose, you're going to learn something. Good luck finding a way to make this happen.