Do you know the condition of the roof, water heaters, etc?

Such as one faulty furnace, 3 cracks/leaks in basement walls, several AC visits outside of warranty...quite a few little things as well. 

Construction (stucco siding and tile roofs, I have several 20 year old roofs that should go another 20 years in their sleep, I paid $7500 to reroof a 12 year old property on MN) and age property.

A couple of thoughts:The best quote I recently received for a roof (1,700 square foot ranch - SF BayArea) was about double that of your budget item;  the electrical line item also seems low based on charges I am seeing up here ($100/hr -$120/hr) and what I understand will need to be done (essentially wiring an entire house)

The tank could not be found, so it is unknown if the tank is leaking. 

New roof, upgraded electrical, plumbing, etc.

The reality is your entire portfolio shouldn't go vacant all at once, or need new roofs all at once. 

Dom, for the money (typically $250 to $300) you can't go wrong, they should tell you the age of the roof, the age of the air conditioning unit and any electrical or plumbing issue. 

My capex budget includes roof 25 year life span, appliances and hot water heater 12 year, hvac 20 year life span , bath and kitchen remodel 20 year life span, etc. i use 10%. 

(also the algae or whatever on the roof looks grungy, I'd fix that if possible)Good Luck!