Mooring balls are usually rented but in some cases you can have one installed and call it your own.
In most parts of the country there is no law against anchoring a boat (even forever) as long as it is out of the channel, not in a restricted area, has current registration or documentation and displays a proper anchor light at night. The downside of course is that people may board your boat and steal anything of value or that the anchor may drag or the rode may wear through and the boat may drift away or end up on the beach or rocks.
As far as getting to and from the boat, you could pay someone or you could launch a dinghy or canoe to get to your boat. A guy used to keep a boat anchored not far from my marina and I watched him swim to it a couple times.