I don't think your average Home Depot variety 2*4 (1.75*3.75....) would work. I have gotten fire from using white pine, but it was carefully selected and air dried. I would be very interested in being proven wrong but it wouldn't be my first choice.

Head over to the doweling department instead and see if they have any poplar. Poplar works pretty good for bow drilling because it is soft and, for lack of a better word, fuzzy. A piece of 1 inch should serve as the hearth, and a piece of 1/4 inch should work as the spindle. Use your favorite knife to flatten off the bigger piece so it lays flat.

The bow itself isn't too materials-demanding, it can be any sort of stick. Some people have more luck with an actual "bow", that is, the stick is springy and pulls tension. I prefer my technique, which uses a fairly stiff stick, and I apply the tension with my thumb as I'm drilling. You'll prefer one way or another, a lot of it probably just depends on what you first gain proficiency with. The string can be just about anything if you use the "egyptian" winding: that is, to tie the string to the spindle, and wrap it in both directions several turns. This makes it impossible for the string to slip on the spindle.

I had a thread somewhere in this forum about bow drilling for fire, it talked a lot about notch geometry and technique.

And yeah, fire-from-friction is not easy. Quite a lot of it is based on discovering what you can get in your area that will work. Don't be discouraged! Your first step is to get fire using very good materials (kiln-dried poplar dowels, cotton lint tinder) to learn the technique and to build confidence. Once you have confidence in your ability to make it work with those materials, then is the time to ramp up the difficulty by using "found" things.