I am a professional flooring installer. There are quite a few different costs that are associated in installing a new hardwood floor in a (not new) home.
If your home doesn't have an existing floor, then the average install numbers hold true in St. Louis, Missouri at around $2 - $3 for Nail Down Hardwood/Engineered.
Lets look at the job from start to finish.
Make sure to get a moisture test, try and understand the reason behind this. You must allow your wood floor to acclimate to your home, and the moisture levels should be within the tolerances allowed. If you nail all your wood down while its freezing in your house, then you allow your home to remain open, during 100 degree days with 100% humidty like it gets here, you will have issues. Let your wood sit in your home, at your normal temps, for a couple days. A week if you can.
If you have tear up. This is where the cost can vary greatly. If your home is on wood, you can look in the hear/ac register on the floor and check what all is installed on top of your sub floor.
Here is a general list I use for take up:
Carpet $.20 / sq ft
Vinyl $1.00 / sq ft (If you have more than one layer, usually you can take all up at once, cut with hand saw into smaller easier to pry up pieces. Set your saw to not cut through your subfloor. Buy the 4ft pry bar for $20 at the box stores)
Nail Down HardWood $1.50-$2.50 / sq ft. (The thinner the boards, the more expensive. i.e. 5 inch 3/4 is easier to rip up than 2" 1/4 (3/4 inch wood). More boards = more nails )
Laminate $1.00 / sq ft. This is the easiest take up. You will have to have a place to dump it, but if you have old laminate, you should really consider taking it up yourself. Its simple
Ceramic $2-$4 / sq ft
Nobody wants to tear out old ceramic. If the underlayment is screwed down and glued, well it can get expensive, dusty, and down right dangerous. Wear safety googles.
BUT WAIT!! There is more!
If there is a toilet, that can cost up to $100 to be pulled up, and reinstalled correctly.
There is the issues with the baseboards. Usually this is pulled and rehung for free. Its a great opportunity to have it replaced, it gets banged up pretty bad if the last time it was hung, it was hung up with a million nails. The key is to use a utility knife and cut the top of the base, cutting the calk/base from the paint, so when you pull the base, it doesn't rip the paint up the wall. If your floor was taller before, you will have an issue with your base matching the old paint line. You can buy taller base, or paint!!
I use this calculator to plug in all the values of the take up and installation costs, it gives me a rough estimate. This is android only, I haven't found one I like for apple sorry!
https://play.google.com/store/apps/details?id=dma.flooringcalculator
For installation charges i use this a guide: (All amounts are Per Square Foot)
NailDown Hardwood $2-$3 (depending on width of board)
Carpet $.50 (pattern matches/berbers extra $.25-$1.00 Depending)
Laminate $2 (Cheaper for larger open areas)
Vinyl $1
I hope the info helps!!
D