Typically SF'ers pick an astronomical price out of thin air. 

FlashlightTape measure/Laser measurePaper/Pen/iPadBinocularsReceptacle testerLevelMarbleDroneRespirator/Face Mask/Eye Protection/GlovesAQI testerWater pressure gaugeThermal cameraEndoscope cameraKnife Good list, in addition in my truck; ohm meter, megger, magnehelic, steel ball, air compressor  generator, plus stuff I'm forgetting

Someone to stock supplies, an appliance repair person, heating/air conditioning repair, plumber, lawn care person, carpenter, salesman, and occasionally an electrician. 

There is a soundproofing drywall quietcrete i think, as well as insulation panels, sound dampening paint, and green glue is a compound that you can roll on as well. likely there is no insulation or it wasnt installed well. air gaps equal noise.  

I see window air conditioners.

We’re looking primarily at sfh for air bnb.

Even spite that,  we still got some air of out of some.

Their a/c starting leaking and has missing ductwork, and is blowing air in random places.

We are looking to open up the wall and then raise the floor and plumb 2 heated and cooled air duct lines to the room.

I started this a little over 3 years ago now.I think thorough research, and data will help make educated decisions, and the real winner in this market is finding a mix of at least 2 of the four:  Off market discount, fixer upper, lowball on market offer, or seller financed/subto.Also if you are planning to do it in a populated area I also think its good to take on the idea of not cash flowing for a few years, and also considering air bnb if you want to reduce costs even more.