The throttle quadrant is a group of secondary flight controls that may include air/fuel mixture, carburetor heat, propeller pitch, flaps, thrust reverse, and of course, the throttles. What specifically is included will depend on the particular aircraft model. Commercial airliners generally locate the throttle quadrant at the front of the center pedestal. The controls take the form of levers with knobs or grips of different shapes so pilots can identify each by touch. General aviation aircraft lacking a center pedestal but having side-by-side seating place the quadrant centered and low on the instrument panel. The controls may be lever types or push-pull types. General aviation aircraft with single or tandem seating will often have the quadrant placed on the left side of the cabin. Often it will be a lever style control. Contemporary fighters place the throttle quadrant to the pilot's left where it is easily griped. The control takes the form of a very elaborate lever referred to as a HOTAS control. (HOTAS stands for hands on throttle and stick.) A HOTAS throttle grip is festooned with a variety of switches whose specific functions depend, once again, upon the specific aircraft model, but may include speed brake, radar range, and missile seeker caging/un-caging.
Your options run from buying a complete product to building from scratch with a stop in the middle at unassembled kits. If you're planning on buying, in addition to the normal recreational joystick sources, you might check out two companies that sell kits for throttle quadrants, Beechhurst Industries that markets to the experimental aviation crowd, and the Virtual Reality Aircraft Company. VRAC is offering modular components you might use to build up a custom throttle quadrant.
And then there's my favorite: build it from scratch.