I'd like to replace the counter tops as well and maybe put in a farmhouse sink (but I feel like these kind of upgrades aren't essential for a rental.) 

At that time we found the sink cabinet was water damaged and replaced it (still not 100% sure if Tenant, we took the hit on it), sewer line backed up due to roots and had costs associated with jetting & roto-rooting sewer and hot water heater replaced.  

Typically i look for big rehab projects, some that others may think are getting close to being worthy of demolishing and with some code violations. the specific house im looking at is 1,000SF and I anticipate purchasing and sinking about $25k in a basic reno plus misc., having a total 45k invested(an thats with me doing a good portion of the work). good neighborhood, house needs allot of work but is structurally sound, just has no driveway or garage, this is the big negative for owner/occupants in my opinion. with no garage I believe I can rent it for around $680/month minimum and keep it easily occupied constantly. 

The real kicker is that it had a sink hole repaired at a corner of the house back in 2007.

Here's what I gleaned as a summary of hardening tips for reducing turnover/maintenance costs:panasonic bath fans with timers in bathrooms4 coats of poly on wood floorsdouble door stopstile floors, showers vs surroundssingle lever shower valve vs. doublereplace toilets with steel parts/mechanicals whenever it starts to runKwikset smart keys (some debate over efficacy)door stoppers on all hingesremove pop-up drains and replace with commercial drains2' drain lines from sinks with an accessible clean outbuy a key cutter - maker for $50 on craigslistGranite tile counters - need a diamond polisher and tile sawUsed Fixed vs. friction shower rodsKeyed deadbolt and passage knob on outside doors to prevent accidental lockout5/8' fire core drywall - can't put a fist thru it and its fire-resistant1/4" board to back up towel rodspolyurethane cabinets under sink to pre seal and drain water to the floor2x4 base under cabinets to prevent particle board cabinets from failing where they meet the floorVinyl scrap under sink and up the back wallBest of luck!

They're just people and they're scared too :-)  The BEST day you will ever have in this business is the day you close a deal where you really really helped a person who was sinking! 

The kitchen is so small, that not putting granite in it would have been silly; it cost me 900 for the granite +sink install.

Tub, sink, and toilet all clean, and very little stuff on the floor.

The majority of sinkholes are the result of debris being buried on a property when housed were built.Over the years as the debris decomposes the dirt above sinks in causing the holes.

Chandelier hanging above kitchen sink spliced into an extension cord for power. 3.