That depends on the type of flooring. Is it angle nailed tongue & groove? Free floating glued together (pergo type)? Is it mechanical interlock free floating? Many more types if custom made.
Count on about 30 cents per square foot (not too many custom cuts) for mechanical interlock (armstrong type). A little more for pergo. Angle nailed tongue & groove should cost 70 cents to $1.00 per foot (mostly having the right equipment cost).
This doesn't include finish cost for unfinished flooring.
The installer should have a good miter saw (pre finished flooring destroys blades, so the owner should buy about 1 good one for every 2000 sq ft for the installer to save costs), an on site table saw (ditto on blade, but not as many), a variable speed jig saw, and assorted hand tools for shaping. This is for free floating floor systems.
If it is a tongue and groove nailed floor, include a good flooring nailer and compressor. A 1.5" 18 gauge STAPLER will also work, but it takes an experienced user to set the staples right. Don't trust someone who shoots it with a finish nailer, unless they are truly masters. Then only with a 16 gauge nailer. 18 is too small, 15 splits way too much.
Other custom made flooring may be glued (not recommended unless there isn't a significant cross grain problem), or face nailed. They do make glue flexable enough (more flexable than liquid nails) for spot gluing. Lexel works fine, and they make special adhesives for this. On the last flooring job of this type that I did, the owner bought a massive amount of 3/4 red oak scrap and asked me to turn it into flooring onsite (oh no!). I trued it as much a possible, put buttons of lexel every half foot or so, and faced nailed it with an 18. He wanted it squeaky (thank you Lord!), so I didn't have to do anything in between boards. After sanding with 150 grit, I mixed the sawdust with Minwax Stain/Finish and spread it around with a squeegy. I sanded it again and re stained. Worked suprisingly well. Varethane on top.
Finishing cost vary widely, depending on the type. If a suitable pre finished flooring is available, push this on the owners. It is much more durable (for scratching), and the total cost will be significantly less.
If it is not pre finished, I implore you to suggest oil based stuff made specificly for floors. It will kill the bugs, as well.:-D
I wish that I still had a cartoon that showed doomed people given a choice between eternity in hell and living in their house while it was being renovated. Every body was in the line for hell.
Oh, a price for finishing. Between 70 cents and $2.00 per sq ft, depending on finish.