Does an exterior door let cold air in next to the thermostat?

For investors with slightly different goals than you/Ben, the “$250-$300 is all that works” statement simply is too simplistic.To start splitting hairs, ROC isn’t the only metric that matters- time and effort matters too- popping in a high tech Alexa enabled thermostat is a quick repair, but adding a backsplash takes a decent amount of time, even if the rental premium and cost were the same.

If you pay heat they won't conserve, so be sure to install temperature limiting thermostats. 

Then you will need $500+ in additional materials, $100 new thermostat and they will probably get about $1000 in profit for running business so that will put you very close to 6k.

Things they need to handle are the regular home maintenance items-  light bulbs, sprinkler heads, ants, spiders, spoke detector batteries, batteries in thermostats,  as well as anything they cause- like plugged toilets, etc. 

I notice the oven knob isn't completely in the off position, but that shouldn't matter since the oven gas (unlike the burners) is triggered by the thermostat current, not the knob position.The tenant is a little flaky, but is generally competent in taking care of things, and would  know if she is leaving the range on.

Purchase price: $20,000 Cash invested: $329,000 Sale price: $473,200 Land Purchase in 2012, New Construction SFR built in 2016: Custom designed bespoke single family home. 3 bed 2.5 ba w/ roof deck, Curb-side Electric Car charging station, Sauna, 4 zone Energy efficient smart air system, HRV whole house fresh air system, Above code spray foam and batt insulation, Commercial grade White TPO roofing system, Triple Pane windows and rear sliding door, One of kind custom wood, metal and glass stairwell fabricated on-site, Phillips Hue smart light pockets throughout (compatible with Alexa, google home, Siri etc) 4 smart thermostats controllable remotely via app and Alexa, Google, Siri.

Purchase price: $20,000 Cash invested: $329,000 Sale price: $473,200 Bespoke single family home. 3 bed 2.5 ba w/ roof deck, Curb-side Electric Car charging station, Sauna, 4 zone Energy efficient smart air system, HRV whole house fresh air system, Above code spray foam and batt insulation, Commercial White TPO roofing system, Triple Pane windows and rear sliding door, Custom wood, metal and glass stairwell fabricated on-site, Phillips Hue smart light pockets throughout 4 smart thermostat Forever-lawn pet friendly grass on roof, private rear patio deck What made you interested in investing in this type of deal?

Made repairs on HVAC, installed Nest thermostat & doorbell, and laid out garage epoxy floors.

The other good option is a pellet stove set to a thermostat.