It would be nice if you used the Fiesta platform and engine for a convertable.
A two seater (posilbly small seat ,child seat in center rear) 5 speed nice stereo, 15 inch tires for 16000. You couldn't chain them to the lot. 90% of vehicle would come from existing model except for doors and rear of vehicle.
Vehicle would come in manual from transmision to windows to locks to folding top. +40mpg. Then options.