The peau de buffle register or the English lute can be added, though they are rarely called for in the litrature. Harpsichords from a kit. Mass. Compare this to a picture painted by numbers versus a painting by a master. Kits can a good way to build an instrument for someone skilled in the nuances of proper voicing of the plectra and other subtleties involved in the shaping of a piece of furniture into a musical instrument. All to often good kits end up sounding less than pleasing.
Prices range considerably.
Double manual harpsichords will be roughly double that range. You will pay extra for fancy casework, painted soundboards, stands and other items. Buying for a school or church will necessitate purchasing a very well built given the beating institutional instruments take. Be sure that a humidity controlled environment and proper maintenance will be provided as well. There is much to consider and know in order to make a solid purchase decision as well as to be able to take care of the instrument.