I'm not familiar with a cantilevered left, or elevator lift, but the most popular here on the bay is a 2 motor lift like this one. On average you can get a 12k for about $5000 or less, plus $180 - $250 per piling. The basic motor and setup is identical on the 10K and up models but the cables are different. Prices you quoted just seem very high to me, shop it around or build your own. Grainger has the motors, welders can do the rest. Consider installing 2 if you have room, renting the other to pay for them both.