Companies that advertise on TV or colour supplements are the most expensive.
If you live in a hard-water area, there will be at least one local water-softener company. Phone them and say "do you repair water softeners"
If yes, engage with them and see what they sell, and the prices. I am currently using a reconditioned one from such a company.
They may refuse ones they did not supply, especially budget brands from DIY sheds.
The technology is very simple, and they may have an "own brand" with an industry-standard control head. Fleck is AFAIK the most common and parts are easy to get. IME it is only the control head that ever goes wrong and needs servicing as it contains all the moving parts including the valves, meter and timer. When you have seen a few you will recognise it.
Unknown electronic brands may not be repairable.
Salt blocks are much more expensive than pebbles or granules, but are convenient. You can get sacks of salt pebbles delivered by the local firm. Don't ever carry salt in your own car as any specks of spillage cause terrible rust and corrosion. Look inside the delivery van and you will be shocked.