You didn't mention if you're going to the North Rim or South Rim. I'll assume that you want to go to the South Rim (where all the action is). I would recommended the Grand Canyon Railroad RV Park. http://www.thetrain.com/lodging/rv-park/
The website picture is just as the park really is. Clean, convenient, and next to the wonderful town of Williams. They have shopping, restaurants, gas/fuel, market and and the Grand Canyon Railroad that you can ride up to the main visitors station in the Grand Canyon.
Wife and I were there last year and the Price at the time was about $35 each. It's a one time thing. Or you can drive your toad. At the RR station they put on a wild west type show and is interesting. BTW, this is the famous Route 66 that Williams is noted for.
There are other RV campgrounds in the vicinity and are probably less $$ per night but most are dirt/mud sites and still close enough to drive to Williams.
Also, Flagstaff AZ is not too far as well as Sedona AZ. which can both be seen in a day. (2 days max).
Hope this helps....