It really depends on two things; what sort of budget you have and in general, where you're located in that shipping costs can prove troublesome when it comes to such things.
If you've never done or dealt with large illusion equipment I'd suggest you start off with a source like MagicAuction.com which is one of the more reputable sources when it comes to used equipment. The alternative would be to purchase building plans by way of books like the popular Paul Osborne, Jim Steinmeyer and Rand Woodbury texts or, in certain situations you can purchase effect specific plans from certain companies like Owens and Magic-Ventures (Bill Smith).
Do yourself a huge favor and check the legal issues tied to any major prop you invest in, making certain that it came from an authorized source. Most all of Jim Stinemeyer's designs, for an example, can only be purchased through John Gaughan and I think Wellingtons though Bill Smith may be taking some of that weight these days, I'm not certain. On the other hand, I know of no one that has legal rights to produce pieces originally put out by Creative Illusions nor a source from which to obtain plans to said systems.
Technically speaking, no one can legally own and perform the Zig Zag or any other Harbin effect without owning the Harbin Book. . . Harbin was probably the first to make such things "an issue" though some of the contention stems from two chief conflicts; the alluded to theft at his hand of a Percy Abbott prop and vice-versa, the supposed theft by Jim Sommers of the Zig Zag. I wouldn't be until issues cropped up around the Origami Box that a major industry wide sense of legal control and royalty honors came into our world as a constant. Unfortunately, such issues have robbed magic of its innocence and freedom as well.
As has been mentioned, the Mark Wilson Course touches on some basics illusion systems that are still quite viable. You'll likewise find routines and "plans" in the Tarbell Course, several of which are quite cool simply because they are rare.
Be prepared to "deal with these things". . . they aren't cheap! Aside from the up-front investment you must have a reliable assistant or two, storage, transport, rehearsal space and ultimately, insurance and maintenance budgets. If you move more into full-time show production you will also need to have a damned good accountant on your side so as to defray your investments when it comes to taxes. . .
Lot's and lots involved when you move down this path!
