I do only rental rehabs taking a 1975+ split level 3/2 and just causemetic;  paint, fixtures, flooring, new HVAC, rarely a roof, never windows,  paint the kitchen cabinets with new hardware, clean up baths, just clean up landscaping, fix things beyond replacing all ceiling and plumbing fixtures (except shower valves) and this has grown to $25k is now tight

With the current lumber and fixture prices the old numbers in many of the fix/flip and BRRRR calculators will get you buried.

-Demo kitchen cabinets-Remove all fixtures-Demo old bathroom tiling and fixtures-Have digging/tunneling prepared for sewage line replacement-Pressure wash outside of house to prep for paintWeeks 2 & 3-Complete sewage line replacement-Begin Landscaping design-Replace entire homes fascia boards-Remove popcorn ceiling textureWeek 5-Have exterior of home painted-Roof leaks should be repaired by nowWeek 7-Have new lighting and fixtures installed-Tile Flooring throughout installed-Replace drywall boards as needed-Paint interiorWeek 9-Kitchen cabinets/countertops and island installed-Bathroom tiling completed-Shower doors installed-Detail work inside-Electrical outlets upgraded-Front Door replaced-Vanities/bath fixtures installedWeek 12-Install appliances-Install Fencing where needed(using about 80% of the neighbors white pvc fence as a privacy, will match)-Paver driveway to be completedWeek 13-Stage for marketing photos and open houses-Accept offer at 110% of list priceI know this is a brief run over of the work, but any advice in planning/ executing is appreciated.

And then get a plumber to install the plumbing fixture to the sink (additional $300). 

I updated the basement by adding laminate flooring and built a bar and added some light fixtures.

I'm really interested in knowing what causes that jump.Can you break down the $18,000 per day to remodel a bathroom by just changing the fixtures, painting, and a little tile?

very tough to do right now. there was a wholesaler over in Salida LA who posted about spending 10k on direct mail finding many leads  NONE would work for flippers and referring them off to an agent who then listed and sold them and of course the agent cannot legally pay a non licensed agent a referral fee other than a cup of coffee.. so there you have someone spending 10k thinking wholesaling was the bee's knees generating market leads which are the vast majority then giving all that away and not making a dime.. 

We renovated the upstairs bathroom and made fixture and hardware changes throughout the house.

Any investor-friendly (good pricing, contractor cash accounts with discounted pricing, etc) supplier recommendations for various materials (flooring, tile, stone, countertop materials, hardscaping, lumber, windows, fixtures, roofing materials, etc) is greatly appreciated!

Biggest job was be replacing the plumbing to shower/tub diverters/fixture, as we had to tear it all out & that usually require new walls.