Not to be terribly unhelpful, but affordable means different things for different people. I suppose it all depends on how you want to travel and what level of accommodations you want. If you are interested in camping, then check out the National Parks website for information about car camping sites in and around the Grand Canyon. That’s what I did, about 10 years ago, and it was really cheap-we also had a camping stove and cooked our own food. If you’re willing to do that, it’s very affordable by most people’s standards. I haven’t stayed in hotels around there, so I can’t speak to that. I do know that there are also a lot of RV campsites around, if that interests you. Good luck planning your trip! Do take a look at the National Parks website, it can be quite helpful. Your local library should also have a bunch of guidebooks that can give you a better idea of prices of hotels, restaurants, etc., if that’s what you’re interested in.