All Eotechs are a bit spendy ($300-$500). If you don't want to spend that much, the Vortex and Primary Arms knockoffs of Aimpoints are reportedly pretty good for $100-$150.
The big problem with cheap Walmart red dots is parallax. If your eye is not centered in the lens, parallax issues can cause the dot to be several inches off from the point of aim. Aimpoint corrects for parallax with a lens between the eye and the reflecting surface, and Eotech corrects for parallax via the hologram. You will not have that correction on a $29.95 Tasco, though.