Rentals on bottles for infrequent use is an expensive option. The up front cost IS higher purchasing however, in a couple of years or three at most, the rental fees would have paid for the bottle.
By good quality gear, American made Smith, Victor or Harris are the most common. A single stage set from any of these brands would be a good choice.
Unless you want to gas weld consider propane or other fuel gas, acetylene has become very expensive and, for heating and cutting is not necessary. If you want to gas weld what max thickness do you need? The amount of acetylene you can draw from a bottle is a limiting factor in torch size.
This thread should give you a better idea of the limitations on acetylene use.
http://www.garagejournal.com/forum/showthread.php?t=327764
Steve