NEw user with really OLD equipment

I have a 50 year old 15,000 gunite pool, sand filter, single speed pump, maintained with chlorine tablets and muriatic acid; the same equipment and chemicals that I used almost 50 years ago! My 3rd Kreepy in 28 years just bit the dust. I need to replace the cleaner for now, but I also have to replace the <1 hp pump, and update/convert this system. So, I am trying to learn what the ins and outs of the BBB system are, and the easiest way to convert. My pool man was NOT thrilled with any of my suggestions, so I am doing my own research. I just figured out that every piece of equipment is dependent on the next- you seem to discuss (almost) "packages", with the cleaning system dependent on the pump size. etc. The only piece of equipment that I will probably not replace is my new pre-filter. The quote for my pool is $1,500 for a new pump, $1,000 for a new filter, and whatever the Keepy runs. Really? Where to start? Thanks. Any feedback would be appreciated.