Is this is an established company? Right now and for the last few months, reputable companies have been swamped and cannot take on new work immediately. Desperate companies will take on any work and generally is not good. That holds true for any home improvement business.

Some things I noticed n the quote. No equipment brand name. The size and model of the filter. A 1.5 HP pump is over sized for even the largest DE filter. Are they not providing wiring of the pool equipment?

50% down when ordering kit? So does that mean 1/2 of the pool kit itself cost? Price of kit is not listed.

You get should at least 2 more estimates. Your budget of $60-$80K could possibly put you in a gunite pool instead of a vinyl.