One of the most common and widely used marketing items is a brochure. If you are going to have any print materials at all, brochures are right up there with business cards and letterhead.
It is an oddity that the word brochure is used most commonly these days for something that is not, technically a brochure at all. The 8-1/2x11, single sheet, tri-fold brochure should really be called a flyer. Brochures by definition are supposed to be multiple sheets (look up the derivation of the word!). But that is a losing battle.
Brochures can range from the very inexpensive to the extraordinarily expensive. Custom sizes, classy paper, multiple pages and all sorts of special effects such as cutouts and spot UV (shiny coating in select areas) can drive up costs as high as $10 each.
It all depends on how you are going to use them, what your budget is and what kind of impression you need to make.
An 8-1/2x11 trifold on cheap paper just won't do if you are trying to promote a multi-million dollar piece of equipment.
Another important point about brochures. Just as the home page of a website needs to get the viewer into the site, the face of a brochure needs to get the reader into it. Everything on the face of a brochure should be designed to make it inevitable that a true prospect will open it up and read on.