Go to a real lumberyard---not Home Depot/Lowe's/Menards/etc. The yard will had at least two sizes---by length----to minimize waste. Here in Kansas City, oak stair treads start at $26. The leading edges of treads have a bullnosed profile. That profile is quite simple to do on the ends with a router and roundover bit.

There is often more to that job than simply removing the old treads and installing the new. Depending on how the old treads were installed, for instance. There is also the height of each step to consider---as that is an extremely important part of a stairway. Normal height is 7" or so, there is a variance allowed by the building codes.

The risers(the vertical parts of the stairs) may need to be removed to take off the old treads. That can easily damage them and then new risers are necessary.

To install risers, I drill holes---generally three for each stringer(the sawtoothed supports for the stairs)put rosin paper over the stringers(to eliminate squeaks) and use #10 screws at least 3" long to install each tread. I then use the plugs I made, using scraps from the treads, to fill the screw holes---carefully aligning the grain pattern. Sand them smooth, apply stain, and then finish. Takes a day to do the installation and staining, and three trips in three days to apply the finish(to allow drying time).

For a simple stair such as yours, one man, one day and three trips---I'd charge $350 for labor if there were no complications. But, I run a retirement5 remodeling business---more something to keep me busy than to earn a living.

handymac I wish I were in Kansas. I have an estimate of 2500 to do just the work you describe without the staining (includes the lumber). Around here there's still a building boom so it's not a buyer's market. Thank you for the info.