Not sure what your waterfront area is like, but at my old house I built my own. It was a bit ghetto of a build, but worked well.
I built a raft on the beach so it would float on a high tide. Essentially I lashed a bunch of logs together. I also happened to have an old chunk of dock that washed ashore and used that for a flat platform on top. I then put a 200l storage tub on the raft. I got access to a bunch of really heavy chain, about 50lbs a link, and put that into the storage tub, with an end hanging out. I encased this in concrete, leaving a decent amount of length exposed as the base of my ground chain. I also exposed another half link from the concrete in case I needed another spot to attach to the mooring. I also lashed/shackled the chain together in the tub, on the off chance the concrete decided to break up so there would still be a large weight on it. I attached more ground chain to the large chain and then ran smaller chain to the surface. I left enough large chain out so that at a 0 or negative tide I could expose the shackles to check everything, and also so the large chain was really all my boat pulled on, and never the actual anchor. This just gives you peace of mind and the ability to check it a few times a year without throwing on the dive gear.
I let the concrete set a day or two. To get this all in the drink where I wanted, I tied the raft to shore, then used a very very long rope tied to the end of my chain, pulled it off with my boat. I managed the position of the mooring by adjusting the shore rope. This process scared the crap out of me, but actually went really smooth. I also was using about 300' of rope to drop it in 30' of water so the worst that could really happen is the mooring went down in the wrong spot.
All in all it worked out better than i had hoped and was really cheap to do, if you don't mind being a bit ghetto. Most of my weight from this was due to the large chain, not the concrete. I think that the concrete in a 200l tub would only be 1000lbs, and under water that loses ~50%. Steel doesn't really change ( or so the internet tells me
). So you may want to go bigger if you don't have large chain to use. Also when building your raft use more logs. Many many more. My first attempt didn't float very well, so waited and added more.
Take all of this information with a grain of salt. In no way am I an expert mooring person, a safety expert or someone to take advice from