I live about 6 hours from the Park and we take all of our company there. I drove to Akron, Ohio in 2 days last fall, so I know it can be done. We usually stay in West Yellowstone for about $100/night - you are not going to find anything much cheaper close to the park. I know people do it, but I would not camp in a tent in or near the park because of the bears. If you want to PM me, I can let you know where we stay and some of the ways we have made it a bit more affordable. I have also traveled out to MN & WI often so I know some of the nice, affordable places to stay along both the ND & SD routes. You definitely should do it if you can. It is worth the trip!