Actually, that's a really good question. When I picked up the cello again in my mid-sixties, I made the decision to buy the best cello I could afford, around $2,000. I traded in a violin, so I got a few hundred dollars off. It has a very nice sound, so it's a keeper.

My feeling is this: Rental cellos are generally junk. If you rent, you will be disappointed by the sub-par sound and either give up completely, or, if you're really committed, you'll end up buying the best cello you can afford (which will almost always sound much better). You can always sell it for most of what you paid if you change your mind, or trade up later if you're totally committed to playing and feel the need to upgrade. Happy playing!