Let's pick the AC compressor and water heater... one bigger expense, one medium expense.  

If occupied it's pretty much just whatever you can tell from the street (ie. roof condition, is the ac compressor there?  

New HVAC (furnace+outside compressor) - no vents, say a 3 ton systemNew HVAC (furnace+outside compressor) - existing vents, 3 ton systemNew HVAC (split system, per room) - without having a 220 service outside alreadyNew windows - All i know about replacing windows is window world charges $189Installing new cabinetry in the kitchen - Assuming I provide cabinets (sub question: Ikea?)

Tell them what you need done and see if they can help.When I was in college, I often went to Labor Ready and did odd jobs like dragging around a 400lb sod compressor and the like. 

I’d start with barring unforeseen circumstances in regards to your quote on the outlet (my preferred method since it allows for different brand EVa as well as high end air compressors,welders, etc.) you’re getting hosed. 

What I find to usually be the biggest difference is the company that’s willing to vacuum out the system and only replace the compressor/condenser half and install r410a freon.

I take a 185 cfm air compressor and blow the water lines , drain hot water tank , and rv antifreeze in traps .

Or a super thin shells that vibrate whenever the compressor kicks in.) 

If the temp exceeds a certain threshold I know that either the power is out or the compressor has died. 

The plumber hooks up a compressor to the plumbing line and fills it with air.