With four seats, a whole aircraft parachute, latest touchscreen avionics, and a cruise speed of 170 mph, the high-tech Sling TSi is the plane of the future. At Custom Aircraft Builders, you can customize every aspect of your plane: paint scheme, interior, avionics & other options, all for under $400K. To build a Sling TSi with flat-rate Builder Assistance costs about $360,000.