Renting/buying parking spaces in Manhattan?

Been parking my car in the Battery Parking Garage for a long time now (8+ years). Like them for the wealth of parking spaces and self-park abilities. Started thinking more seriously about other parking options recently and it would seem that the only upgrades from my current situation would be: a. Rent a space in a privately owned garage (might be easier to find a unicorn) b. Buy a space (but no idea where to start looking or what the costs would be) Reasonably easy access from my apt downtown in Tribeca would be a requirement. Am I overreaching here? Where do I start looking?