First, you are in the wrong forum, Second if you can wait for the new IRA inflation reduction act coming out next year they are offering front end cash rebates up to $8000 for heat pumps, it seems the current tax credits are being stolen by the contractors by making you sign it over to them or in an up-charge, basically negating any credit or rebate as seen in your $8k quote.

Thirdly, if looking for a DIY system that still comes with a 10 year warranty when self installing, look at the MrCool Universal system, a complete 2-ton split system heat pump including air handler with plug & play line set is about $3000.

It is a completely sealed system that only requires a couple of hand tools and nothing else, or about $2300 without the new air handler box. I can usually install these in about 4 hours depending on your existing layout.