Ok... are you looking for a trick in which the mirror is a focal point or are you interested in effects that rely on mirrors as part of the method? There seems to be some confusion on that point.
EFFECTS WITH A MIRROR A THE FOCUS depend on how big you wish to go as well as personal budget, time, and possible craftsmanship skills should you decide to build something of significant size. . . which I'd assume given your use of the term "Illusion" which as a rule, implies large-scaled effects such as
Walking Thru a
Mirror/
Mirror Penetrations (Click each word in title for 5 different version), , Creating a Living Reflection or even causing someone to vanish by first making their reflection in the mirror fade away. . . Depending on the kind of effect and the version you decide to work with, you're looking at a low-end investment of around $500.00 to a top end price somewhere between $15,000.00 and as much as $25,000.00. If you'd like a very neat exclusive there is a very novel piece that combines
Franz's 2-D technology with a Mirror Penetration -- the catch is, you end up trapped inside the mirror, the audience actually sees you inside the glass, moving.
EFFECTS WITH A MIRROR GIMMICK rang from the classic "Drum Production" type arrangement, a series of
Carnival Sideshow Freaks, the "
Suit Case" (one of my favorites)
Feel free to IM me if you have any questions, a few of these pieces can be made for cheap.