I'm sorry, but that is a really tough one. When it comes to purchasing (or even just trading for) reproduction props there are too many different variables. How accurate is the reproduction? How good is the quality (fit and finish) of the final work? Are they good about meeting deadlines and sending stuff when promised? These things and more have to be considered. (And no, technically most prop builders are not legitimate in the sense they are making unlicensed products.)
The best recommendation I can give is to check out the various prop boards and ask around. The prop community is a relatively small one and over time prop builders develop reputations. Since different people have different ideas of what is a "great" reproduction, try to find one that is universally regarded as good. Just be prepared to pay a premium price as a result.

We used the Jin Roh art book (especially the black and white line drawings) for reference when making our outfits. The molds were made from ultracal plaster (harder than plaster of paris but otherwise similar) and bondo. The plastic was either styrene (easier to work with) or ABS plastic (more durable). The eyes were done using superbright LEDs. The machine guns we carried were replica MG-34s that we made out of aluminum, plastic resin and fiberglass. They also used MG-42s which we don't have but plan to replicate in the future.
However it took six of us working three months before the vacform molds were complete, and another two months per person after that to make finished copies. That's about twenty man-months to produce one copy, so it really isn't worthwhile for a single person. Vacforming really is designed for making multiple copies of an item rather than a single one-off. To make your own outfit it might be better to try something similar to the Bubblegum Crisis Boomer that was at AnimeExpo--my understanding is it was made entirely of found items that were cut to shape and painted. It will take some time to find all the pieces but try not to get discouraged. Instead of having a specific deadline like next year's Expo, concentrate more on trying to make the best outfit you can. There will always be an Expo or other con you can then show it off at. Good luck, and let me know if I can offer further help.

Thanks for the compliments. Believe it or not, you are one of the few people who have read the disclaimer and respected it. Although we are open to trades, I frequently get curt emails from people essentially saying, "How much for the costume?"
Our goal has always been to make the best reproductions we can. We originally premiered the Jin-Roh creations at Fanime 2002. What most people don't realize is that we spent the two months between Fanime and Anime Expo redoing major parts of the outfits to make them even better. (For example, we weren't happy with the leather strapping and completely replaced it.) Few people would even notice the difference but we knew and it would bug us if we left it as is. Even now the Jin-Roh outfits are far from complete, and there are more detail bits we plan to add in the future.
Unfortunately this level of attention to detail means new creations are a long time in coming. Chances are we won't have a new creation ready for Anime Expo for a couple years (if then) but when we do, you can be sure we'll have given it our best shot.

Hi, nice to hear from you. First and foremost we are a group of friends with likeminded interests. That we are all members of a prop building group is almost secondary. Having said that, we're always willing to help people learn prop building techniques. I have a vacforming setup and you or your friends are welcome to drop by to see how it's done and maybe pick up a few techniques. Unfortunately I live in Santa Cruz. Mat lives in Fremont and I'm sure he'd be willing to give you a similar demo if you ask him.

How did your costume turn out? Although we try to plan for events, we're no strangers to last-minute crash jobs in order to get things done. We were still painting/assembling our Jin-Roh armor literally two hours before the cosplay event. [grin]
I'm glad to hear your attitude towards our work. We've met some people at cons who semi-jokingly ask us what projects we're working on in order to avoid doing the same stuff. Some of us have been building props for over a decade and we constantly strive to make "hero-level" props--or better. It's amazing what kind of flaws film can hide whereas our stuff has to survive close scrutiny from the people we meet. And even there we often go the extra distance to rework/improve details that most people would never notice unless we pointed it out to them. A couple members have gone on to work professionally in the prop-building industry but for most of us it really is a hobby we do in our spare time.
We are always open to learning new techniques and more than willing to help teach them to others. That's why we created the "Techniques" section of our website and hold prop-building panels at various cons we attend. We all started out as beginners. If we can help other people do what we do then the entire prop building community benefits. So if you have any questions, feel free to ask.