For halloween last fall, Jaimi and I decided to do a Tony Stark/Pepper Potts combo. The idea was to have a low maintenance costume that was also fairly accurate. We already have likenesses similar to Downey Jr. and Paltrow, so there were minor cosmetic changes to be made.
As for the costumes, I finally had an excuse to buy a suit. I hit up Kohl's during a sale and got a lightly pinstriped affair. The only addition to this was a pocket square that got pinned to the pocket. Jaimi had to do a little bit more shopping around to get the right match of business garments.
As for props, I got the Iron Man T-Shirt from think geek. It has the arc reactor light that velcros into the chest and a battery pack that attaches at the bottom of the shirt. I cut out the fabric in the arc reactor,becuase I planned on wearing a shirt over it. Jaimi's "Stark Industries Tablet" is a Light Wedge that began its career as a book light. I had noticed that the minor scratches on it glowed a bit, so we printed a design, taped it to the back, and scratched the design with an exacto knife.
The finishing touches included a carefully trimmed goatee and some fussing with our hair.
Bonus: Tony Stark + Commander Shepard