New York Helicopter

I am planning a trip to Las Vegas in a couple weeks and we are driving. We plan to stop at the Grand Canyon on the way home. I am interested in an inexpensive tour while we are there but everything I find online is tours departing and returning to Vegas. I do not want a helicopter tour. Can I just show up at the Grand Canyon and walk around on my own or must I purchase some sort of tour package? I would ideally like a walking tour. Thanks.
Please so comments about the South Rim. I am planning on seeing the West Rim and the Skywalk. I only plan on being there a couple hours, just stopping on my way home.
Please NO comments about the South Rim.