I'm a caver and have a lot of vertical caving gear, but it is not a major part of my survival gear. However, it does have its place. Bob and Bob is the major caving supply source in the USA. Go for PMI or Bluewater ropes. A rappel rack is the safest device that has ever been invented. It can be used for drops over 1,000 feet such as the deep pits in Mexico, or a skyscraper such as the Empire State Building. If I worked in a high rise building, I would have my gear in my office.